U.S. patent number 11,248,138 [Application Number 16/463,526] was granted by the patent office on 2022-02-15 for printing ink formulations, preparation methods and uses thereof.
This patent grant is currently assigned to Guangzhou Chinaray Optoelectronic Materials Ltd.. The grantee listed for this patent is GUANGZHOU CHINARAY OPTOELECTRONIC MATERIALS LTD.. Invention is credited to Junyou Pan, Xiaolin Yan, Xi Yang.
United States Patent |
11,248,138 |
Pan , et al. |
February 15, 2022 |
Printing ink formulations, preparation methods and uses thereof
Abstract
A printing ink formulation includes a functional material and a
solvent being evaporable from the printing ink formulation to form
a functional material thin film. The solvent is formed by mixing at
least two organic solvents including a first solvent and a second
solvent. The solvent system containing at least two solvents can
effectively dissolve the functional material without the need of
adding an additive, and can also effectively prevent the occurrence
of a "coffee-ring effect", and accordingly, the thin film
containing a uniform thickness and a strong electron transmission
capability can be obtained.
Inventors: |
Pan; Junyou (Guangdong,
CN), Yang; Xi (Guangdong, CN), Yan;
Xiaolin (Guangdong, CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
GUANGZHOU CHINARAY OPTOELECTRONIC MATERIALS LTD. |
Guangdong |
N/A |
CN |
|
|
Assignee: |
Guangzhou Chinaray Optoelectronic
Materials Ltd. (Guangdong, CN)
|
Family
ID: |
62195731 |
Appl.
No.: |
16/463,526 |
Filed: |
November 23, 2017 |
PCT
Filed: |
November 23, 2017 |
PCT No.: |
PCT/CN2017/112702 |
371(c)(1),(2),(4) Date: |
May 23, 2019 |
PCT
Pub. No.: |
WO2018/095381 |
PCT
Pub. Date: |
May 31, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190375956 A1 |
Dec 12, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
Nov 23, 2016 [CN] |
|
|
201611051757.9 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
51/0077 (20130101); C09D 11/037 (20130101); C09D
11/322 (20130101); H01L 51/0067 (20130101); H01L
51/0056 (20130101); H01L 51/0058 (20130101); H01L
51/0059 (20130101); H01L 51/0072 (20130101); C09D
11/50 (20130101); C09K 11/565 (20130101); H01L
51/0085 (20130101); C09K 11/06 (20130101); C09D
11/033 (20130101); C09K 11/54 (20130101); C09D
11/52 (20130101); C09D 11/36 (20130101); C09K
11/883 (20130101); H01L 51/5012 (20130101); C09K
2211/1029 (20130101); H01L 51/5072 (20130101); H01L
51/5088 (20130101); H01L 51/5056 (20130101); H01L
51/5096 (20130101); H01L 33/28 (20130101); C09K
2211/185 (20130101); H01L 51/0005 (20130101); H01L
51/5092 (20130101); H01L 33/04 (20130101); H01L
51/5016 (20130101) |
Current International
Class: |
C09D
11/36 (20140101); C09D 11/033 (20140101); C09K
11/06 (20060101); C09K 11/08 (20060101); H01L
51/00 (20060101); C09D 11/50 (20140101); C09D
11/037 (20140101); C09D 11/322 (20140101); C09D
11/52 (20140101); C09K 11/54 (20060101); C09K
11/56 (20060101); C09K 11/88 (20060101); H01L
33/04 (20100101); H01L 33/28 (20100101); H01L
51/50 (20060101) |
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|
Primary Examiner: Nguyen; Vu A
Attorney, Agent or Firm: Cozen O'Connor
Claims
The invention claimed is:
1. A printing ink formulation, comprising a functional material and
a solvent, the solvent could be evaporable from the printing ink
formulation to form a functional film; wherein the solvent is
formed by mixing at least two organic solvents including a first
solvent and a second solvent, the first solvent and the second
solvent are miscible, and at least one of the first solvent and the
second solvent has a boiling point greater than or equal to
160.degree. C., the second solvent has a surface tension less than
that of the first solvent and a viscosity greater than that of the
first solvent, and the difference in surface tension between the
first solvent and the second solvent is at least 2 dyne/cm, and the
difference in viscosity between the second solvent and the first
solvent is at least 2 cPs, wherein the functional material is an
inorganic nanomaterial or an organic functional material, and
wherein the organic functional material is selected from the group
consisting of hole injection materials, hole transport materials,
electron transport materials, electron injection materials,
electron blocking materials, hole blocking materials, emitters,
host materials, and organic dyes.
2. The printing ink formulation according to claim 1, wherein at
least one of the first solvent and the second solvent has a surface
tension between 19 dyne/cm and 50 dyne/cm at 25.degree. C.
3. The printing ink formulation according to claim 1, wherein at
least one of the first solvent and the second solvent has a
viscosity between 1 cPs and 100 cPs at 25.degree. C.
4. The printing ink formulation according to claim 1, wherein the
first solvent is present in an amount between 30 wt % and 90 wt %
based on the total weight of the solvent, and the second solvent is
present in an amount between 10 wt % and 70 wt % based on the total
weight of the solvent.
5. The printing ink formulation according to claim 1, wherein the
first solvent or the second solvent is each independently selected
from the group consisting of a substituted or unsubstituted
aromatic solvent, a substituted or unsubstituted heteroaromatic
solvent, an aromatic ketone solvent, an aromatic ether solvent,
ester solvent, a linear aliphatic solvent, an alicyclic solvent, an
aliphatic ketone solvent, an aliphatic ether solvent, an alcohol
solvent, and an inorganic ester solvent.
6. The printing ink formulation according to claim 5, wherein the
substituted or unsubstituted aromatic solvent is selected from the
group consisting of p-diisopropylbenzene, pentylbenzene,
tetrahydronaphthalene, cyclohexylbenzene, chloronaphthalene,
1,4-dimethylnaphthalene, 3-isopropylbiphenyl,
p-methylisopropylbenzene, dipentylbenzene, o-diethylbenzene,
m-diethylbenzene, p-diethylbenzene, 1,2,3,4-tetramethylbenzene,
1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene,
butylbenzene, dodecylbenzene 1-methylnaphthalene,
1,2,4-trichlorobenzene, 1,3-dipropoxybenzene,
4,4-difluorodiphenylmethane, 1,2-dimethoxy-4-(1-propenyl)benzene,
diphenylmethane, N-methyldiphenylamine, 4-isopropylbiphenyl,
.alpha.,.alpha.-dichlorodiphenylmethane, benzyl benzoate,
1,1-bis(3,4-dimethylphenyl)ethane, 2-isopropylnaphthalene, dibenzyl
ether, and 2-isopropyl naphthalene; the substituted or
unsubstituted heteroaromatic solvent is selected from the group
consisting of 2-phenylpyridine, 3-phenylpyridine,
4-(3-phenylpropyl)pyridine, quinoline, isoquinoline,
8-hydroxyquinoline, methyl 2-furancarboxylate, and ethyl
2-furancarboxylate; the aromatic ketone solvent is selected from
the group consisting of: 1-tetralone, 2-tetralone, acetophenone,
propiophenone or benzophenone, the 1-tetralone or 2-tetralone is
each independently, optionally substituted by a substituent of an
aliphatic group, an aryl group, a heteroaryl group or a halogen;
the acetophenone, propiophenone or benzophenone is each
independently, optionally substituted by a methyl group; the
aromatic ether solvent is selected from the group consisting of
3-phenoxytoluene, butoxybenzene, benzyl butylbenzene,
p-anisaldehyde dimethyl acetal, tetrahydro-2-phenoxy-2H-pyran,
1,2-dimethoxy-4-(1-propenyl)benzene, 1,4-benzodioxane,
1,3-dipropylbenzene, 2,5-dimethoxytoluene, 4-ethylphenetole,
1,2,4-trimethoxybenzene, 4-(1-propenyl)-1,2-dimethoxybenzene,
1,3-dimethoxybenzene, glycidyl phenyl ether, dibenzyl ether,
4-tert-butylanisole, trans-p-propenyl anisole,
1,2-dimethoxybenzene, 1-methoxynaphthalene, diphenyl ether,
2-phenoxymethyl ether, 2-phenoxytetrahydrofuran, and
ethyl-2-naphthyl ether; the ester solvent is selected from the
group consisting of alkyl octanoate, alkyl sebacate, alkyl
stearate, alkyl benzoate, alkyl phenylacetate, alkyl cinnamate,
alkyl oxalate, alkyl maleate, alkyl lactone, and alkyl oleate; the
cycloaliphatic solvent is selected from the group consisting of
tetrahydronaphthalene, cyclohexylbenzene, decahydronaphthalene,
2-phenoxytetrahydrofuran, 1,1'-bicyclohexane, butylcyclohexane,
ethyl rosinate, benzyl rosinate, ethylene glycol carbonate, styrene
oxide, isophorone, 3,3,5-trimethylcyclohexanone, cycloheptanone,
fenchone, 1-tetralone, 2-tetralone, 2-(phenyl epoxy)tetralone, 6-(m
ethoxy)tetralone, .gamma.-butyrolactone, .gamma.-valerolactone,
6-caprolactone, N,N-diethyl cyclohexylamine, sulfolane, and
2,4-dimethylsulfolane; the aliphatic ketone solvent is selected
from the group consisting of 2-nonanone, 3-nonanone, 5-nonanone,
2-decanone, 2,5-hexanedione, di-n-pentyl ketone, phorone,
isophorone, 2,6,8-trimethyl-4-nonanone, camphor, and fenchone; the
aliphatic ether solvent is selected from the group consisting of
pentyl ether, hexyl ether, dioctyl ether, ethylene glycol dibutyl
ether, diethylene glycol diethyl ether, diethylene glycol butyl
methyl ether, diethylene glycol dibutyl ether, triethylene glycol
dimethyl ether, triethylene glycol ethyl methyl ether, triethylene
glycol butyl methyl ether, tripropylene glycol dimethyl ether, and
tetraethylene glycol dimethyl ether; the inorganic ester solvent is
selected from the group consisting of tributyl borate, tripentyl
borate, trimethyl phosphate, triethyl phosphate, tributyl
phosphate, tris(2-ethylhexyl) phosphate, triphenyl phosphate,
diethyl phosphate, dibutyl phosphate, and
di(2-ethylhexyl)phosphate.
7. The printing ink formulation according to claim 6, wherein the
second solvent is 1-tetralone and the first solvent is quinolone or
isoquinolone; or, the second solvent is 3-phenoxytoluene and the
first solvent is selected from the group consisting of
chlorophthalene, styrene oxide, quinoline and isoquinoline; or, the
second solvent is 3-isopropylbiphenyl, and the first solvent is
selected from the group consisting of 3-phenoxytoluene,
acetophenone, tetrahydronaphthalene, chloronaphthalene,
1,4-dimethylnaphthalene, 1-methylnaphthalene, diphenyl ether,
diphenylmethane, 2-isopropylnaphthalene, styrene oxide, quinoline
and isoquinoline; or, the second solvent is isononyl isononanoate,
the first solvent is selected from the group consisting of
3-phenoxytoluene, acetophenone, pentylbenzene,
tetrahydronaphthalene, cyclohexylbenzene, chloronaphthalene,
o-diethylbenzene, dodecylbenzene, diphenyl ether, diphenylmethane,
2-isopropylbenzene, octyl octanoate, 1,1-bicyclohexane,
butyrolactone, isophorone, cycloheptanone and triethyl phosphate;
or, the second solvent is sulfolane, and the first solvent is
selected from the group consisting of 3-phenoxytoluene,
acetophenone, chloronaphthalene, 1,4-dimethylnaphthalene,
1-methylnaphthalene, diphenyl ether, ethylene glycol carbonate,
quinoline and isoquinoline; or, the second solvent is
dodecylbenzene, and the first solvent is selected from the group
consisting of acetophenone, tetrahydronaphthalene,
chloronaphthalene, 1-methylnaphthalene, diphenylmethane,
butyrolactone, isophorone and isoquinoline; or, the second solvent
is 2,4-dimethyl sulfolane, and the first solvent is selected from
the group consisting of 3-phenoxytoluene, acetophenone,
pentylbenzene, cyclohexylbenzene, chloronaphthalene,
diethylbenzene, xylene, dichlorobenzene, dodecylbenzene,
trichlorobenzene, diphenyl ether, diphenylmethane,
2-isopropylnaphthalene, 1,1-bicyclohexane, butyrolactone,
cycloheptanone, quinoline, isoquinoline and triethyl phosphate.
8. The printing ink formulation according to claim 7, wherein the
second solvent is 1-tetralone and the first solvent is quinolone;
or, the second solvent is 3-phenoxytoluene and the first solvent is
chloronaphthalene; or, the second solvent is 3-isopropylbiphenyl
and the first solvent is acetophenone; or, the second solvent is
isononyl isononanoate and the first solvent is pentylbenzene; or,
the second solvent is sulfolane and the first solvent is
3-phenoxytoluene; or, the second solvent is dodecylbenzene and the
first solvent is tetrahydronaphthalene.
9. The printing ink formulation according to claim 7, wherein
weight ratio of the first solvent to the second solvent is between
40:60 and 80:20.
10. The printing ink formulation according to claim 1, wherein the
solvent further comprises methanol, ethanol, 2-methoxyethanol,
dichloromethane, trichloromethane, chlorobenzene,
o-dichlorobenzene, tetrahydrofuran, anisole, morpholine, toluene,
o-xylene, m-xylene, p-xylene, 1,4-dioxane, acetone, methyl ethyl
ketone, 1,2-dichloroethane, 3-phenoxytoluene,
1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, ethyl acetate,
butyl acetate, dimethylformamide, dimethylacetamide, dimethyl
sulfoxide, tetrahydronaphthalene, decalin, indene, or mixtures
thereof.
11. The printing ink formulation according to claim 1, wherein
weight ratio of the functional material in the printing ink
formulation is between 0.3 wt % and 30 wt %; the weight ratio of
the solvent in the printing ink formulation is between 70 wt % and
99.7 wt %.
12. The printing ink formulation according to claim 1, wherein the
inorganic nanomaterial is a quantum dot material with a
monodisperse size distribution and has a shape selected from
sphere, cube, rod, and branched structure.
13. The printing ink formulation according to claim 12, wherein the
quantum dot material is a semiconductor nanocrystal; the
semiconductor nanocrystal comprises at least one semiconductor
material; and the semiconductor material is selected from binary or
multiple semiconductor compounds or mixtures thereof of Group IV,
II-VI, II-V, III-V, III-VI, IV-VI, I-III-VI, II-IV-VI, II-IV-V of
the periodic table.
14. The printing ink formulation according to claim 13, wherein the
inorganic nanomaterial is selected from the group consisting of
perovskite nanomaterials, metal nanoparticle materials, metal oxide
nanoparticle materials, and mixtures thereof.
15. The printing ink formulation according to claim 1, wherein the
organic functional material comprises at least one host material
and at least one emitter.
16. The printing ink formulation according to claim 1, wherein at
least one of the first solvent or the second solvent is represented
by the following formula: ##STR00099## wherein, Ar.sup.1 is an
aromatic containing 5 to 10 ring atoms or heteroaromatic containing
5 to 10 ring atoms, n 1 and R is a substituent.
17. The printing ink formulation according to claim 1, wherein the
functional material is an inorganic semiconductor nanomaterial.
18. The printing ink formulation according to claim 1, wherein the
difference in surface tension between the first solvent and the
second solvent is at least 4 dyne/cm.
19. The printing ink formulation according to claim 1, wherein the
printing ink formulation has a surface tension in the range from 19
dyne/cm to 50 dyne/cm at 25.degree. C.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a national stage for International
Application PCT/CN2017/112702, filed on Nov. 23, 2017, which claims
priority benefit of Chinese Patent Application No. 201611051757.9,
entitled "A Printing Electronic Formulation" and filed on Nov. 23,
2016, the entire content of both applications are incorporated
herein for all purposes.
TECHNICAL FIELD
The present disclosure relates to the field of organic
optoelectronic materials, and in particular to printing ink
formulations, preparation methods thereof, and uses thereof.
BACKGROUND
The organic light-emitting diode (OLED), as a new generation
display technology, is usually prepared by evaporation method. The
manufacturing process has low material utilization rate, and
requires a fine metal mask (FMM), thus having higher cost and lower
yield. In order to solve the above problems, a technique for
realizing high-resolution full-color display using a printing
process has been received more and more attention. For example,
inkjet printing, which may produce a functional material film in a
large area and at low cost, and has lower energy consumption and
lower water consumption thus being environment-friendly compared
with conventional semiconductor production process, is a production
technology with great advantages and potential. Quantum dot
light-emitting diode (QLED), which is another new display
technology, cannot be evaporated and must be prepared by printing.
Therefore, to achieve printed display, it is necessary to break
through key issues such as printing ink and related printing
processes. Viscosity and surface tension are important parameters
that affect the printing ink and printing processes. A promising
printing ink needs to have the proper viscosity and surface
tension.
Organic semiconductor materials have gained widespread attention
and significant progress in their use in electronic and
optoelectronic devices due to their solution processability.
Solution process allows the organic functional material to be
capable of forming thin films in the device by coating or printing
techniques. Such technologies may effectively reduce the processing
cost of electronic and optoelectronic devices, and meet the process
requirements of large-area preparation. Currently, there are
several companies reported the organic semiconductor material ink
used for printing, for example: KATEEVA, INC. discloses an ester
solvent-based organic small molecule material ink for printable
OLED (US2015044802A1); UNIVERSAL DISPLAY CORPORATION discloses a
printable organic small molecular material ink based on an aromatic
ketone or an aromatic ether solvent (US20120205637); SEIKO EPSON
CORPORATION discloses a printable organic polymer material ink
based on a substituted benzene derivative solvent. Other examples
relate to an organic functional material printing ink are:
CN102408776A, CN103173060A, CN103824959A, CN1180049C, CN102124588B,
US2009130296A1, US2014097406A1, etc.
Another kind of functional materials that are suitable for printing
are inorganic nanomaterials, particularly quantum dots. Quantum
dots are nano-sized semiconductor materials with quantum
confinement effect. A quantum dot would emit fluorescence with
specific energy when stimulated by light or electricity. The color
(energy) of the fluorescence is determined by the chemical
formulation and size of the quantum dot. Therefore, the control of
the size and shape of quantum dot can effectively regulate its
electrical and optical properties. Recently, electroluminescent
device with quantum dots as light emitting layer (QLED) has been
rapidly developed, and device lifetime thereof has been greatly
improved, as reported in Peng et al., Nature Vol 515 96 (2015) and
Qian et al., Nature Photonics Vol 9 259 (2015). Currently, several
companies have reported quantum dot inks for printing: Nanoco
Technologies Ltd. discloses a method for preparing printable ink
formulation comprising nanoparticles (CN101878535B), the printable
nanoparticle ink and the corresponding nanoparticle-containing film
are obtained by selecting suitable solvents such as toluene and
dodecyl selenol; Samsung Electronics discloses a quantum dot ink
for inkjet printing (U.S. Pat. No. 8,765,014B2) containing a
concentration of quantum dot material, organic solvent, and alcohol
polymer additive having a high viscosity, by printing the ink, a
quantum dot film is obtained and a quantum dot electroluminescent
device is prepared; QD Vision, Inc. discloses a quantum dot ink
formulation comprising a host material, a quantum dot material and
an additive (US2010264371A1).
Other patents relating to quantum dot printing inks comprise:
US2008277626A1, US2015079720A1, US2015075397A1, TW201340370A,
US2007225402A1, US2008169753A1, US2010265307A1, US2015101665A1,
WO2008105792A2. In these published patents, in order to regulate
the physical parameters of the ink, these quantum dot inks contain
other additives such as alcohol polymers. The introduction of
polymer additives with insulating properties tends to reduce the
charge transport capability of the film, which has a negative
impact on the optoelectronic properties of the device, and limits
its wide application in optoelectronic devices.
In addition, in the process of inkjet printing and drying process,
it is often accompanied by a "coffee ring effect", that is, the
solute material is easily deposited on the edge of the droplet,
resulting in the dried thin film having a thick edge and a thin
center. This is because during the drying process, the solvent
mainly evaporates from the edge of the droplet, and the volume
change of the solution mainly occurs at the center of the droplet,
which in turn causes the solution to flow from the center to the
edge. The obtained film having a non-uniform thickness is extremely
disadvantageous for further processing of the optoelectronic
devices and device performance. Therefore, the search for a
suitable solvent system to reduce the "coffee ring effect" of
inkjet printed films is particularly important for improving the
uniformity of the film and device performance.
SUMMARY
In accordance with various embodiments of the present application,
a printing ink formulation, a preparation method thereof, and uses
thereof are provided that solves one or more of the problems
involved in the background.
A printing ink formulation comprises a functional material and a
solvent, the solvent could be evaporable from the printing ink
formulation to form a functional material film;
the solvent is formed by mixing at least two organic solvents
including a first solvent and a second solvent, the first solvent
and the second solvent are miscible, at least one of the first
solvent and the second solvent has a boiling point of
>160.degree. C., the second solvent has a surface tension less
than that of the first solvent and a viscosity greater than that of
the first solvent, the difference in surface tension between the
second solvent and the first solvent is at least 2 dyne/cm, and the
difference in viscosity between the second solvent and the first
solvent is at least 2 cPs.
A method for preparing the above formulation comprises:
1) dissolving any solid component contained in the functional
material into the first solvent, and
2) adding the second solvent to the first solvent in which the
solid component has been dissolved to form a mixed solution.
An electronic device comprises a functional layer, which is a
functional material film prepared from the printing ink formulation
described above, is also provided.
BRIEF DESCRIPTION OF THE DRAWINGS
The FIGURE is a schematic view of an electronic device according to
an embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The objects, technical solution and advantages of the present
application will become more apparent and understandable by further
describing the present disclosure in detail with reference to the
accompanying drawings and embodiments. It should be noted that, the
specific embodiment illustrated herein is merely for the purpose of
explanation, and should not be deemed to limit the disclosure.
In the present disclosure, terms of "formulation", "printing ink
formulation" and "printing ink" or "ink" have the same meaning and
are interchangeable.
In the present disclosure, terms of "host material" or "matrix
material" or "Host" or "Matrix" have the same meaning and are
interchangeable.
In the present disclosure, terms of "metal organic clathrate",
"metal organic complexes", and "organometallic complexes" have the
same meaning and are interchangeable.
In the present disclosure, "@ 25.degree. C." means that the
measurement is carried out at 25.degree. C.
A printing ink formulation, comprises a functional material and a
solvent, the solvent could be evaporable from the printing ink
formulation to form a functional material film;
the solvent is formed by mixing at least two organic solvents
including a first solvent and a second solvent, the first solvent
and the second solvent are miscible, at least one of the first
solvent and the second solvent has a boiling point of
.gtoreq.160.degree. C., the second solvent has a surface tension
less than that of the first solvent and a viscosity greater than
that of the first solvent, the difference in surface tension
between the second solvent and the first solvent is at least 2
dyne/cm, and the difference in viscosity between the second solvent
and the first solvent is at least 2 cPs.
In an embodiment, at least one of the first solvent and the second
solvent has a boiling point of .gtoreq.160.degree. C.; in an
embodiment, at least one of the first solvent and the second
solvent has a boiling point of .gtoreq.180.degree. C.; in some
embodiments, at least one of the first solvent and the second
solvent has a boiling point of .gtoreq.200.degree. C.; in another
embodiment, at least one of the first solvent and the second
solvent has a boiling point of .gtoreq.250.degree. C.; in another
embodiment, at least one of the first solvent and the second
solvent has a boiling point of .gtoreq.275.degree. C.; in another
embodiment, at least one of the first solvent and the second
solvent has a boiling point of .gtoreq.300.degree. C.
In an embodiment, both the first solvent and the second solvent
have a boiling point of .gtoreq.160.degree. C.; in an embodiment,
both the first solvent and the second solvent have a boiling point
of .gtoreq.180.degree. C.; in an embodiment, both the first solvent
and the second solvent have a boiling point of .gtoreq.200.degree.
C.; in an embodiment, both the first solvent and the second solvent
have a boiling point of .gtoreq.220.degree. C.; in an embodiment,
both the first solvent and the second solvent have a boiling point
of .gtoreq.240.degree. C.
Selecting a solvent having a boiling point within the above range
may prevent clogging of the nozzle of the inkjet print head.
In an embodiment, a formulation comprising at least two organic
solvents, at least one of which has a viscosity in the range of 1
cPs to 100 cPs @25.degree. C. That is, at 25.degree. C., at least
one of the first solvent and the second solvent has a viscosity
from 1 cPs to 100 cPs.
In an embodiment, at least one of the first solvent and the second
solvent has a viscosity from 1 cPs to 50 cPs; in an embodiment, at
least one of the first solvent and the second solvent has a
viscosity from 1 cPs to 40 cPs; in an embodiment, at least one of
the first solvent and the second solvent has a viscosity from 1 cPs
to 30 cPs; in an embodiment, at least one of the first solvent and
the second solvent has a viscosity from 1.5 cPs to 20 cPs. The
viscosity herein refers to the viscosity at the time of printing at
ambient temperature, in an embodiment, in the range from 15.degree.
C. to 30.degree. C.; in an embodiment, in the range from 18.degree.
C. to 28.degree. C.; in an embodiment, in the range from 20.degree.
C. to 25.degree. C.; in an embodiment, in the range from 23.degree.
C. to 25.degree. C. The formulation so formulated will be
particularly suitable for inkjet printing.
In some embodiments, in the formulation according to the present
disclosure, at least one of the first solvent and the second
solvent has a surface tension from 19 dyne/cm to 50 dyne/cm at
25.degree. C.
Specific substrate and specific printing methods require suitable
surface tension parameters of formulations. For example, for inkjet
printing, in an embodiment, at least one of the two organic
solvents has a surface tension from 19 dyne/cm to 50 dyne/cm at
25.degree. C.; in an embodiment, at least one of the two organic
solvents has a surface tension from 22 dyne/cm to 35 dyne/cm at
25.degree. C.; in an embodiment, at least one of the two organic
solvents has a surface tension from 25 dyne/cm to 33 dyne/cm at
25.degree. C.
In another embodiment, both the organic solvents have a surface
tension from 19 dyne/cm to 50 dyne/cm at 25.degree. C.; in another
embodiment, both the organic solvents have a surface tension from
22 dyne/cm to 35 dyne/cm at 25.degree. C.; in another embodiment,
both the organic solvents have a surface tension from 25 dyne/cm to
33 dyne/cm at 25.degree. C.
In an embodiment, the printing ink formulation has a surface
tension in the range from 19 dyne/cm to 50 dyne/cm at 25.degree.
C.; in an embodiment, the printing ink formulation has a surface
tension in the range from 22 dyne/cm to 35 dyne/cm at 25.degree.
C.; in an embodiment, the printing ink formulation has a surface
tension in the range from 25 dyne/cm to 33 dyne/cm at 25.degree.
C.
A solvent system comprising at least two organic solvents
satisfying the above boiling point and viscosity parameters is
comprised in the printing ink formulation to form a functional
material film with uniform thickness and formulation property.
In addition, a printing ink formulation comprises at least two
organic solvents, a first solvent and a second solvent, the second
solvent having a less surface tension than that of the first
solvent, and the second solvent having a greater viscosity than
that of the first solvent, resulting in a film of functional
material having a uniform thickness distribution during inkjet
printing and drying.
In an embodiment, the first solvent is a good solvent for the
functional material.
In an embodiment, both the first solvent and the second solvent are
good solvents for the functional material.
The good solvent means that the solubility is .gtoreq.1.0 wt %,
further .gtoreq.1.5 wt %, still further .gtoreq.2.0 wt %, even
further .gtoreq.2.2 wt %.
The disclosure also relates to a method for preparing the printing
ink formulation as described above.
According to the method, a method for preparing the formulation as
described above comprises the following steps:
1) dissolving any solid component contained in the functional
material into a first solvent, and
2) adding a second solvent to the first solvent in which the solid
component has been dissolved to form a mixed solution.
According to the above method, an ink of functional material
capable of suppressing edge flow and improving the uniformity of
the inkjet-printed film can be obtained.
According to this method, the first solvent used has a relatively
good solubility to the functional material, ensuring sufficient
solubility and stability of the functional material in the
solution. The first solvent used has a higher boiling point to
prevent clogging of the nozzle during printing and to ensure
stability during injection of the solution.
During the process of inkjet printing and drying into a film, it is
often accompanied by a "coffee ring effect", that is, the solute
material is easily deposited on the edge of the droplet, resulting
in the dried thin film having a thick edge and a thin center. This
is because during the drying process, the solvent mainly evaporates
from the edge of the droplet, and the volume change of the solution
mainly occurs at the center of the droplet, which in turn causes
the solution to flow from the center to the edge. To this end, the
dual solvent system of the present invention needs to
simultaneously satisfy:
(1) at least one of the first solvent and the second solvent has a
boiling point of .gtoreq.160.degree. C.;
(2) the second solvent has a surface tension less than that of the
first solvent and a viscosity greater than that of the first
solvent.
The possible mechanisms by which it suppresses the "coffee ring
effect" are as follows:
(1) during the drying process of inkjet printing the formulation to
the substrate, at least one high boiling point solvent may
prolonged the drying time of the droplets of solution, increase the
time during which the solute is freely diffused from the high
concentration region to the low concentration region in the
droplets, reduce the uneven distribution of the solute during the
drying process, and improve the uniformity of the inkjet-printed
deposited film;
(2) the high flow resistance due to the high viscosity of the
second solvent can effectively reduce the edge flow strength of the
solution and suppress the edge deposition of the solute, thereby
improving the uniformity of the inkjet-printed deposited film and
effectively suppressing the "coffee ring" effect;
Further, since the surface tension of the second solvent is smaller
than that of the first solvent, a tendency of an increase in the
surface tension from the edge to the center may be formed on the
surface of the solution droplet during drying of the ink ejected to
the substrate, thereby driving the surface solution to flow from
the edge to the center. This creates an annular convection with the
flow from the center to the edge inside the solution. Such annular
convection is beneficial to the uniform distribution of functional
materials during the drying process, which can effectively reduce
the deposition of functional materials at the edges and weaken the
"coffee ring effect", so that the dried functional material film
has good uniformity and flatness.
In an embodiment, the printing ink formulation as described above,
in which the second solvent has a less surface tension than that of
the first solvent, and the second solvent has a greater viscosity
than that of the first solvent.
In order to achieve the above-described high flow resistance to
suppress the "coffee ring" effect, in an embodiment, the difference
in viscosity between the second solvent and the first solvent is at
least 2 cPs.
In an embodiment, the difference in viscosity between the second
solvent and the first solvent is at least 4 cPs.
In an embodiment, the difference in viscosity between the second
solvent and the first solvent is at least 6 cPs.
In an embodiment, the difference in viscosity between the second
solvent and the first solvent is at least 8 cPs.
In an embodiment, the difference in viscosity between the second
solvent and the first solvent is at least 10 cPs.
In an embodiment, the difference in surface tension between the
second solvent and the first solvent is at least 2 dyne/cm.
In an embodiment, the difference in surface tension between the
second solvent and the first solvent is at least 4 dyne/cm.
In an embodiment, the difference in surface tension between the
second solvent and the first solvent is at least 6 dyne/cm.
In an embodiment, the difference in surface tension between the
second solvent and the first solvent is at least 8 dyne/cm.
In an embodiment, the difference in surface tension between the
second solvent and the first solvent is at least 2 dyne/cm, while
the difference in viscosity between the second solvent and the
first solvent is at least 2 cPs.
In an embodiment, the difference in surface tension between the
second solvent and the first solvent is at least 4 dyne/cm, while
the difference in viscosity between the second solvent and the
first solvent is at least 4 cPs.
In an embodiment, the difference in surface tension between the
second solvent and the first solvent is at least 6 dyne/cm, while
the difference in viscosity between the second solvent and the
first solvent is at least 6 cPs.
In an embodiment, the difference in surface tension between the
second solvent and the first solvent is at least 8 dyne/cm, while
the difference in viscosity between the second solvent and the
first solvent is at least 8 cPs.
In the printing ink formulation as described above, the first
solvent is present in an amount from 30% to 90% of the total weight
of the solvent, and the second solvent is present in an amount from
10% to 70% of the total weight of the solvent. In an embodiment,
the second solvent is present in an amount from 20% to 60% of the
total weight of the solvent; in an embodiment, the second solvent
is present in an amount from 20% to 50% of the total weight of the
solvent, in an embodiment, the second solvent is present in an
amount from 20% to 40% of the total weight of the solvent.
In an embodiment, the second solvent having a boiling point higher
than that of the first solvent.
In an embodiment, the second solvent having a boiling point at
least 10.degree. C. higher than that of the first solvent. In an
embodiment, the second solvent having a boiling point at least
20.degree. C. higher than that of the first solvent. In an
embodiment, the second solvent having a boiling point at least
30.degree. C. higher than that of the first solvent. In an
embodiment, the second solvent having a boiling point at least
40.degree. C. higher than that of the first solvent. In an
embodiment, the second solvent having a boiling point at least
50.degree. C. higher than that of the first solvent. In an
embodiment, the second solvent having a boiling point at least
60.degree. C. higher than that of the first solvent.
In another embodiment, the first solvent has a higher boiling point
than that of the second solvent. In an embodiment, the first
solvent having a boiling point at least 10.degree. C. higher than
that of the second solvent. In an embodiment, the first solvent
having a boiling point at least 20.degree. C. higher than that of
the second solvent. In an embodiment, the first solvent having a
boiling point at least 30.degree. C. higher than that of the second
solvent.
In an embodiment, at least one of the two organic solvents
comprised in the formulation according to the present disclosure is
based on an aromatic or heteroaromatic solvent.
In another embodiment, the printing ink formulation comprises at
least two organic solvents, in which at least one of the organic
solvents is represented by the following formula:
##STR00001##
wherein,
Ar.sup.1 is an aromatic containing 5 to 10 ring atoms or
heteroaromatic containing 5 to 10 ring atoms, n.gtoreq.1 and R is a
substituent.
In some embodiments, in the organic solvent is represented by the
formula (I), Ar.sup.1 is an aromatic containing 5 to 9 ring atoms
or heteroaromatic containing 5 to 9 ring atoms. The aromatic group
refers to a hydrocarbyl comprising at least one aromatic ring,
including monocyclic group and polycyclic ring system. A
heteroaromatic group refers to a hydrocarbyl group (containing a
heteroatom) containing at least one heteroaromatic ring, including
a monocyclic group and a polycyclic ring system. Such polycyclic
rings may have two or more rings in which two carbon atoms are
shared by two adjacent rings, i.e., a fused ring. At least one of
such polycyclic rings is aromatic or heteroaromatic.
Specifically, examples of the aromatic group include: benzene,
naphthalene, anthracene, phenanthrene, perylene, tetracene, pyrene,
benzopyrene, triphenylene, acenaphthene, fluorene, and derivatives
thereof.
Specifically, examples of the heteroaromatic group include: furan,
benzofuran, thiophene, benzothiophene, pyrrole, pyrazole, triazole,
imidazole, oxazole, oxadiazole, thiazole, tetrazole, indole,
carbazole, pyrroloimidazole, pyrrolopyrrole, thienopyrrole,
thienothiophene, furopyrrole, furofuran, thienofuran,
benzisoxazole, benzisothiazole, benzimidazole, pyridine, pyrazine,
pyridazine, pyrimidine, triazine, quinoline, isoquinoline,
cinnoline, quinoxaline, phenanthridine, perimidine, quinazoline,
quinazolinone, and derivatives thereof.
In an embodiment, the formulation comprises an organic solvent
represented by the formula (I), and it may be further represented
by the following formula (II) to formula (VI):
##STR00002##
wherein,
X is CR.sup.1 or N;
Y is selected from CR.sup.2R.sup.3, SiR.sup.4R.sup.5, NR.sup.6 or
C(.dbd.O), S, or O.
R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6 are
independently selected from the group consisting of H, D, or a
linear alkyl containing 1 to 10 C atoms, linear alkoxy containing 1
to 10 C atoms or linear thioalkoxy group containing 1 to 10 C
atoms, or a branched or cyclic alkyl containing 3 to 10 C atoms,
branched or cyclic alkoxy containing 3 to 10 C atoms or branched or
cyclic thioalkoxy group containing 3 to 10 C atoms or silyl group
containing 3 to 10 C atoms, or a substituted ketone group
containing 1 to 10 C atoms, or an alkoxycarbonyl group containing 2
to 10 C atoms, or an aryloxycarbonyl group containing 7 to 10 C
atoms, or a cyano group (--CN), a carbamoyl group (--C(.dbd.O)NH2),
a haloformyl group (--C(.dbd.O)--X wherein X represents a halogen
atom), a formyl group (--C(.dbd.O)--H), an isocyano group, an
isocyanate group, an thiocyanate group or an isothiocyanate group,
an hydroxyl group, an nitro group, an CF.sub.3 group, Cl, Br, F, a
crosslinkable group or a substituted or unsubstituted aromatic ring
system containing 5 to 10 ring atoms or substituted or
unsubstituted heteroaromatic ring system containing 5 to 10 ring
atoms, or an aryloxy group containing 5 to 10 ring atoms or
heteroaryloxy group containing 5 to 10 ring atoms, or a combination
thereof.
Wherein, one or more of the groups R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, R.sup.6 may form a monocyclic or polycyclic
aliphatic or aromatic ring system with each other and/or with a
ring bonded thereto.
In an embodiment, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5,
R.sup.6 are independently selected from the group consisting of H,
D, or a linear alkyl containing 1 to 6 C atoms, linear alkoxy
containing 1 to 6 C atoms or linear thioalkoxy group containing 1
to 6 C atoms, or a branched or cyclic alkyl containing 3 to 6 C
atoms, branched or cyclic alkoxy containing 3 to 6 C atoms or
branched or cyclic thioalkoxy group containing 3 to 6 C atoms or
silyl group containing 3 to 6 C atoms, or a substituted ketone
group containing 1 to 6 C atoms, or an alkoxycarbonyl group
containing 2 to 6 C atoms, or an aryloxycarbonyl group containing 7
to 10 C atoms, or a cyano group (--CN), a carbamoyl group
(--C(.dbd.O)NH2), a haloformyl group (--C(.dbd.O)--X wherein X
represents a halogen atom), a formyl group (--C(.dbd.O)--H), an
isocyano group, an isocyanate group, an thiocyanate group or an
isothiocyanate group, an hydroxyl group, an nitro group, an
CF.sub.3 group, Cl, Br, F, a crosslinkable group or a substituted
or unsubstituted aromatic ring system containing 5 to 8 ring atoms
or substituted or unsubstituted heteroaromatic ring system
containing 5 to 8 ring atoms, or an aryloxy group containing 5 to 8
ring atoms or heteroaryloxy group containing 5 to 8 ring atoms, or
a combination of these groups. The groups R.sup.1, R.sup.2,
R.sup.3, R.sup.4, R.sup.5, R.sup.6 may form a monocyclic or
polycyclic aliphatic or aromatic ring system with each other and/or
with a ring bonded thereto.
In an embodiment, Ar.sup.1 in formula (I) is selected from
following structural units:
##STR00003##
In some embodiments, at least one substituent R in formula (I) is
selected from the group consisting of a linear alkyl containing 1
to 10 C atoms, linear alkoxy containing 1 to 10 C atoms or linear
thioalkoxy group containing 1 to 10 C atoms, or a branched or
cyclic alkyl containing 3 to 10 C atoms, branched or cyclic alkoxy
containing 3 to 10 C atoms or branched or cyclic thioalkoxy group
containing 3 to 10 C atoms or silyl group containing 3 to 10 C
atoms, or a substituted ketone group containing 1 to 10 C atoms, or
an alkoxycarbonyl group containing 2 to 10 C atoms, or an
aryloxycarbonyl group containing 7 to 10 C atoms, or a cyano group
(--CN), a carbamoyl group (--C(.dbd.O)NH2), a haloformyl group
(--C(.dbd.O)--X wherein X represents a halogen atom), a formyl
group (--C(.dbd.O)--H), an isocyano group, an isocyanate group, an
thiocyanate group or an isothiocyanate group, an hydroxyl group, an
nitro group, an CF.sub.3 group, Cl, Br, F, a crosslinkable group or
a substituted or unsubstituted aromatic ring system containing 5 to
10 ring atoms or substituted or unsubstituted heteroaromatic ring
system containing 5 to 10 ring atoms, or an aryloxy group
containing 5 to 10 ring atoms or heteroaryloxy group containing 5
to 10 ring atoms, or a combination of these groups. R may form a
monocyclic or polycyclic aliphatic or aromatic ring system with
each other and/or with a ring bonded thereto.
In an embodiment, at least one substituent R in formula (I) is
selected from the group consisting of a linear alkyl containing 1
to 6 C atoms, linear alkoxy containing 1 to 6 C atoms or linear
thioalkoxy group containing 1 to 6 C atoms, or a branched or cyclic
alkyl containing 3 to 6 C atoms, branched or cyclic alkoxy
containing 3 to 6 C atoms or branched or cyclic thioalkoxy group
containing 3 to 6 C atoms or silyl group containing 3 to 6 C atoms,
or a substituted ketone group containing 1 to 6 C atoms, or an
alkoxycarbonyl group containing 2 to 6 C atoms, or an
aryloxycarbonyl group containing 6 to 7 C atoms, or a cyano group
(--CN), a carbamoyl group (--C(.dbd.O)NH2), a haloformyl group
(--C(.dbd.O)--X wherein X represents a halogen atom), a formyl
group (--C(.dbd.O)--H), an isocyano group, an isocyanate group, an
thiocyanate group or an isothiocyanate group, an hydroxyl group, an
nitro group, an CF.sub.3 group, Cl, Br, F, a crosslinkable group or
a substituted or unsubstituted aromatic ring system containing 5 to
8 ring atoms or substituted or unsubstituted heteroaromatic ring
system containing 5 to 8 ring atoms, or an aryloxy group containing
5 to 8 ring atoms or heteroaryloxy group containing 5 to 8 ring
atoms, or a combination of these groups. One or more of group R may
form a monocyclic or polycyclic aliphatic or aromatic ring system
with each other and/or with a ring bonded thereto.
In an embodiment, the aromatic or heteroaromatic solvent is
selected from the group consisting of p-diisopropylbenzene,
pentylbenzene, tetrahydronaphthalene, cyclohexylbenzene,
chloronaphthalene, 1,4-dimethylnaphthalene, 3-isopropylbiphenyl,
p-methylisopropylbenzene, dipentylbenzene, o-diethylbenzene,
m-diethylbenzene, p-diethylbenzene, 1,2,3,4-tetramethylbenzene,
1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene,
butylbenzene, dodecylbenzene 1-methylnaphthalene,
1,2,4-trichlorobenzene, 1,3-dipropoxybenzene,
4,4-difluorodiphenylmethane, 1,2-dimethoxy-4-(1-propenyl)benzene,
diphenylmethane, 2-phenylpyridine, 3-phenylpyridine,
N-methyldiphenylamine, 4-isopropylbiphenyl,
.alpha.,.alpha.-dichlorodiphenylmethane,
4-(3-phenylpropyl)pyridine, benzyl benzoate,
1,1-bis(3,4-dimethylphenyl)ethane, 2-isopropylnaphthalene, dibenzyl
ether, 2-isopropyl naphthalene, quinoline, isoquinoline,
8-hydroxyquinoline, methyl 2-furancarboxylate, ethyl
2-furancarboxylate and the like.
In an embodiment, at least one of the two organic solvents
comprised in the formulation is an organic solvent based on an
aromatic ketone.
In an embodiment, the aromatic ketone solvent is tetralone, such as
1-tetralone and 2-tetralone.
In other embodiments, the tetralone solvent comprises a derivative
of 1-tetralone and 2-tetralone, i.e., tetralone substituted by at
least one substituent. These substituents include an aliphatic
group, an aryl group, a heteroaryl group, a halogen, and the
like.
In an embodiment, the aromatic ketone solvent is selected from
2-(phenyl epoxy)tetralone or 6-(methoxy) tetralone.
In other embodiments, the aromatic ketone solvent is selected from
acetophenone, propiophenone, benzophenone, and derivatives
thereof.
In an embodiment, the solvent of the aromatic ketone is selected
from the group consisting of 4-methylacetophenone,
3-methylacetophenone, 2-methylacetophenone, 4-methylpropiophenone,
3-methylpropiophenone, and 2-methylpropiophenone.
In other embodiments, at least one of the two organic solvents
comprised in the printing ink formulation is a ketone solvent that
do not contain aromatic or heteroaromatic groups, such as
isophorone, 2,6,8-trimethyl-4-nonanone, camphor, and fenchone.
In an embodiment, at least one of the two organic solvents
comprised in the formulation is an organic solvent based on an
aromatic ether.
The aromatic ether solvent is selected from the group consisting of
3-phenoxytoluene, butoxybenzene, benzyl butylbenzene,
p-anisaldehyde dimethyl acetal, tetrahydro-2-phenoxy-2H-pyran,
1,2-dimethoxy-4-(1-propenyl)benzene, 1,4-benzodioxane,
1,3-dipropylbenzene, 2,5-dimethoxytoluene, 4-ethylphenetole,
1,2,4-trimethoxybenzene, 4-(1-propenyl)-1,2-dimethoxybenzene,
1,3-dimethoxybenzene, glycidyl phenyl ether, dibenzyl ether,
4-tert-butylanisole, trans-p-propenyl anisole,
1,2-dimethoxybenzene, 1-methoxynaphthalene, diphenyl ether,
2-phenoxymethyl ether, 2-phenoxytetrahydrofuran, and
ethyl-2-naphthyl ether.
In an embodiment, the aromatic ether solvent is
3-phenoxytoluene.
In an embodiment, at least one of the two organic solvents
comprised in the formulation is an organic solvent based on an
ester.
The ester solvent is selected from the group consisting of alkyl
octanoate, alkyl sebacate, alkyl stearate, alkyl benzoate, alkyl
phenylacetate, alkyl cinnamate, alkyl oxalate, alkyl maleate, alkyl
lactone, alkyl oleate, and the like.
In some embodiments, the ester solvent is octyl octanoate or
diethyl sebacate.
In other embodiments, at least one of the two organic solvents
comprised in the printing ink formulation is selected from
aliphatic ketone solvents.
In other embodiments, at least one of the two organic solvents
comprised in the printing ink formulation is selected from
aliphatic ether solvents.
The aliphatic ketone organic solvent may be selected from the group
consisting of 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone,
2,5-hexanedione, 2,6,8-trimethyl-4-nonanone, phorone, di-n-pentyl
ketone, or the like.
The aliphatic ether organic solvent may be selected from the group
consisting of pentyl ether, hexyl ether, dioctyl ether, ethylene
glycol dibutyl ether, diethylene glycol diethyl ether, diethylene
glycol butyl methyl ether, diethylene glycol dibutyl ether,
triethylene glycol dimethyl ether, triethylene glycol ethyl methyl
ether, triethylene glycol butyl methyl ether, tripropylene glycol
dimethyl ether, tetraethylene glycol dimethyl ether or the
like.
In still other embodiments, at least one of the two organic
solvents comprised in the printing ink formulation is selected from
alicyclic solvents.
The cycloaliphatic solvent is selected from the group consisting of
tetrahydronaphthalene, cyclohexylbenzene, decahydronaphthalene,
2-phenoxytetrahydrofuran, 1,1'-bicyclohexane, butylcyclohexane,
ethyl rosinate, benzyl rosinate, ethylene glycol carbonate, styrene
oxide, isophorone, 3,3,5-trimethylcyclohexanone, cycloheptanone,
fenchone, 1-tetralone, 2-tetralone, 2-(phenyl epoxy)tetralone,
6-(methoxy)tetralone, .gamma.-butyrolactone, .gamma.-valerolactone,
6-caprolactone, N,N-diethyl cyclohexylamine, sulfolane, and
2,4-dimethyl sulfolane.
In an embodiment, at least one of the two organic solvents
comprised in the printing ink formulation is selected from
inorganic ester solvents.
The inorganic ester solvent is selected from the group consisting
of tributyl borate, tripentyl borate, trimethyl phosphate, triethyl
phosphate, tributyl phosphate, tris(2-ethylhexyl) phosphate,
triphenyl phosphate, diethyl phosphate, dibutyl phosphate,
di(2-ethylhexyl)phosphate, or the like.
Compared with the conventional solvents (such as toluene, xylene,
chloroform, chlorobenzene, dichlorobenzene, n-heptane, etc.) for
dissolving functional materials, the above solvent systems
containing at least two organic solvents may more effectively
dissolve the functional materials without adding an additive, and
may also effectively prevent the occurrence of "coffee ring
effect", so that a film having uniform thickness and a strong
electron transmission capability can be obtained, which is suitable
for use in photovoltaic devices.
The parameters of boiling point, surface tension and viscosity of
some of the above solvent examples are listed below, but are not
limited thereto:
TABLE-US-00001 Surface Boiling tension Viscosity point @RT @RT name
Structural formula (.degree. C.) (dyne/cm) (cPs) 1-tetralone
##STR00004## 256 42 8.6 3-phenoxytoluene ##STR00005## 272 37.4 5
acetophenone ##STR00006## 202 39 1.6 1-methoxynaphthalene
##STR00007## 270 43 7.2 p-diisopropylbenzene ##STR00008## 210 28.3
1.2 pentylbenzene ##STR00009## 205 30.4 1.3 tetrahydronaphthalene
##STR00010## 207 35.9 2 cyclohexylbenzene ##STR00011## 238 34 4
chloronaphthalene ##STR00012## 260 43 3 1,4-dimethylnaphthalene
##STR00013## 268 40 6 3-isopropylbiphenyl ##STR00014## 296 34 9
p-methyl cumene ##STR00015## 177 28.8 3.4 dipentylbenzene
##STR00016## 255-280 30 4.7 o-diethylbenzene ##STR00017## 183 30
3.8 m-diethylbenzene ##STR00018## 181 29 1.24 p-diethylbenzene
##STR00019## 183 29 3.6 1,2,3,4- tetramethylbenzene ##STR00020##
205 29 2 1,2,3,5- tetramethylbenzene ##STR00021## 205 29 2 1,2,4,5-
tetramethylbenzene ##STR00022## 197 29 2 butylbenzene ##STR00023##
183 29.23 1 dodecylbenzene ##STR00024## 331 30.12 5.4
1-methylnaphthalene ##STR00025## 240 38 3 1,2,4-trichlorobenzene
##STR00026## 214 31 1.6 diphenyl ether ##STR00027## 257 38 3.5
diphenylmethane ##STR00028## 265 37 1.5 4-isopropylbiphenyl
##STR00029## 298 34 9 benzyl benzoate ##STR00030## 324 44 8.3
1,1-bis(3,4-dimethylphenyl) ethane ##STR00031## 333 34 10
2-isopropylnaphthalene ##STR00032## 268 36 4 dibenzyl ether
##STR00033## 298 39 8.7 octyl octanoate ##STR00034## 307 30.1 4.56
diethyl sebacate ##STR00035## 312 32.9 6 diallyl phthalate
##STR00036## 290 39.2 9~13 isononyl isononanoate ##STR00037## 285
27.8 7 decahydronaphthalene ##STR00038## 196 29 3.4
1,1'-bicyclohexane ##STR00039## 239 33 3.75 butylcyclohexane
##STR00040## 181 27 1.2 butyrolactone ##STR00041## 204 35 1.7
ethylene glycol carbonate ##STR00042## 238 37 2 styrene oxide
##STR00043## 194 43 2 isophorone ##STR00044## 215 32 2.6
cycloheptanone ##STR00045## 181 31.5 2.6 fenchone ##STR00046## 193
31 3.6 .quadrature.-valerolactone ##STR00047## 207 29 3.4
6-caprolactone ##STR00048## 215 32 1.1 sulfolane ##STR00049## 287
35 10 2,4-dimethyl sulfolane ##STR00050## 280 28 7.9 quinoline
##STR00051## 237 45 4.3 isoquinoline ##STR00052## 243 46 3.3
tributyl borate ##STR00053## 234 24.5 1.2 tripentyl borate
##STR00054## 275 27.3 2.88 triethyl phosphate ##STR00055## 215 30.2
1.6 triphenyl phosphate ##STR00056## 245 40 11
The embodiments of the dual solvent system are shown in the
following table, but not limited thereto.
TABLE-US-00002 First solvent Second solvent Weight ratio quinoline
1-tetralone 40:60 to 80:20 isoquinoline 40:60 to 80:20
chloronaphthalene 3-phenoxytoluene 40:60 to 80:20 styrene oxide
40:60 to 80:20 quinoline 40:60 to 80:20 isoquinoline 40:60 to 80:20
3-phenoxytoluene 3-isopropylbiphenyl 40:60 to 80:20 acetophenone
40:60 to 80:20 tetrahydronaphthalene 40:60 to 80:20
chloronaphthalene 40:60 to 80:20 1,4-dimethylnaphthalene 40:60 to
80:20 1-methylnaphthalene 40:60 to 80:20 diphenyl ether 40:60 to
80:20 diphenylmethane 40:60 to 80:20 2-isopropylnaphthalene 40:60
to 80:20 styrene oxide 40:60 to 80:20 quinoline 40:60 to 80:20
isoquinoline 40:60 to 80:20 3-phenoxytoluene isononyl isononanoate
40:60 to 80:20 acetophenone 40:60 to 80:20 pentylene 40:60 to 80:20
tetrahydronaphthalene 40:60 to 80:20 cyclohexylbenzene 40:60 to
80:20 chloronaphthalene 40:60 to 80:20 o-diethylbenzene 40:60 to
80:20 dodecylbenzene 40:60 to 80:20 diphenyl ether 40:60 to 80:20
diphenylmethane 40:60 to 80:20 2-isopropylbenzene 40:60 to 80:20
octyl octanoate 40:60 to 80:20 1,1-bicyclohexane 40:60 to 80:20
butyrolactone 40:60 to 80:20 isophorone 40:60 to 80:20
cycloheptanone 40:60 to 80:20 triethyl phosphate 40:60 to 80:20
3-phenoxytoluene sulfolane 40:60 to 80:20 acetophenone 40:60 to
80:20 chloronaphthalene 40:60 to 80:20 1,4-dimethylnaphthalene
40:60 to 80:20 1-methylnaphthalene 40:60 to 80:20 diphenyl ether
40:60 to 80:20 ethylene glycol carbonate 40:60 to 80:20 quinoline
40:60 to 80:20 isoquinoline 40:60 to 80:20 acetophenone
dodecylbenzene 40:60 to 80:20 tetrahydronaphthalene 40:60 to 80:20
chloronaphthalene 40:60 to 80:20 1-methylnaphthalene 40:60 to 80:20
diphenylmethane 40:60 to 80:20 butyrolactone 40:60 to 80:20
isophorone 40:60 to 80:20 isoquinoline 40:60 to 80:20
3-phenoxytoluene 2,4-dimethyl sulfolane 40:60 to 80:20 acetophenone
40:60 to 80:20 pentylene 40:60 to 80:20 cyclohexylbenzene 40:60 to
80:20 chloronaphthalene 40:60 to 80:20 diethylbenzene 40:60 to
80:20 xylene 40:60 to 80:20 dichlorobenzene 40:60 to 80:20
dodecylbenzene 40:60 to 80:20 trichlorobenzene 40:60 to 80:20
diphenyl ether 40:60 to 80:20 diphenylmethane 40:60 to 80:20
2-isopropylnaphthalene 40:60 to 80:20 1,1-bicyclohexane 40:60 to
80:20 butyrolactone 40:60 to 80:20 cycloheptanone 40:60 to 80:20
quinoline 40:60 to 80:20 isoquinoline 40:60 to 80:20 triethyl
phosphate 40:60 to 80:20
In an embodiment, the second solvent is 1-tetralone and the first
solvent is quinoline.
In an embodiment, the second solvent is 3-phenoxytoluene and the
first solvent is chloronaphthalene.
In an embodiment, the second solvent is 3-isopropylbiphenyl and the
first solvent is acetophenone.
In an embodiment, the second solvent is isononyl isononanoate and
the first solvent is pentylbenzene.
In an embodiment, the second solvent is sulfolane and the first
solvent is 3-phenoxytoluene.
In an embodiment, the second solvent is dodecylbenzene and the
first solvent is tetrahy dronaphthalene.
In other embodiments, the solvent comprising the two organic
solvents further comprises another organic solvent selected from
the group consisting of methanol, ethanol, 2-methoxyethanol,
dichloromethane, trichloromethane, chlorobenzene,
o-dichlorobenzene, tetrahydrofuran, anisole, morpholine, toluene,
o-xylene, m-xylene, p-xylene, 1,4-dioxane, acetone, methyl ethyl
ketone, 1,2-dichloroethane, 3-phenoxytoluene,
1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, ethyl acetate,
butyl acetate, dimethylformamide, dimethylacetamide, dimethyl
sulfoxide, tetrahydronaphthalene, decalin, indene, and/or mixtures
thereof.
The printing ink formulation may further comprise one or more other
components, such as a surfactant compound, a lubricant, a wetting
agent, a dispersant, a hydrophobic agent, a binder, to adjust the
viscosity and the film forming property and to improve the adhesion
property.
The printing ink formulation can be deposited into a functional
film by a variety of printing or coating techniques. The
appropriate printing technology or coating technology includes, but
is not limited to inkjet printing, nozzle printing, typography,
screen printing, dip coating, spin coating, blade coating, roller
printing, twist roller printing, lithography, flexography, rotary
printing, spray coating, brush coating or transfer printing, or
slot die coating, and the like. Further, printing techniques are
inkjet printing, nozzle printing and gravure printing. For more
information about printing technologies and relevant requirements
thereof on related inks, such as solvents and concentration,
viscosity, etc., see Helmut Kipphan, et al., Handbook of Print
Media: Technologies and Production Methods, ISBN 3-540-67326-1,
edited by Helmut Kipphan. In general, different printing techniques
have different requirements for the characteristics of the inks
used. For example, a printing ink suitable for inkjet printing
require adjustment of the surface tension, viscosity and
wettability of the ink so that the ink can be sprayed through the
nozzle well at the printing temperature (such as room temperature,
25.degree. C.) without drying on the nozzle or clogging the nozzle,
or can form a continuous, flat and defect-free film on a specific
substrate.
A printing ink formulation according to the present disclosure
comprises at least one functional material.
The functional material may be an organic material or an inorganic
material.
The viscosity can also be adjusted by adjusting the concentration
of the functional material in the formulation. The solvent system
of the present disclosure comprising at least two organic solvents
can facilitate the adjustment of the printing ink in an appropriate
range according to the printing method used.
In an embodiment, the weight ratio of the functional material in
the formulation is from 0.3 wt % to 30 wt %;
In an embodiment, the weight ratio of the functional material in
the formulation is from 0.5 wt % to 20 wt %;
In an embodiment, the weight ratio of the functional material in
the formulation is from 0.5 wt % to 15 wt %;
In an embodiment, the weight ratio of the functional material in
the formulation is from 0.5 wt % to 10 wt %.
In an embodiment, the functional material can be a material having
some optoelectronic functions including, but not limited to, a hole
injection function, a hole transport function, an electron
transport function, an electron injection function, an electron
blocking function, a hole blocking function, a light emitting
function, a host function and a light absorption function. The
corresponding functional materials are referred to as a hole
injection material (HIM), hole transport material (HTM), electron
transport material (ETM), electron injection material (EIM),
electron blocking material (EBM), hole blocking material (HBM),
emitter, host material, and organic dye.
In an embodiment, the functional material comprised in the printing
ink formulation is an inorganic nanomaterial.
In an embodiment, the inorganic nanomaterial in the printing ink
formulation is an inorganic semiconductor nanoparticle
material.
In an embodiment, the inorganic nanomaterial has an average
particle size in the range from about 1 to 1000 nm. In another
embodiment, the inorganic nanomaterial has an average particle size
in the range from about 1 to 100 nm. In another embodiment, the
inorganic nanomaterial has an average particle size in the range
from about 1 to 20 nm. In another embodiment, the inorganic
nanomaterial has an average particle size in the range from about 1
to 10 nm.
The inorganic nanomaterial may be in different shapes, and may have
different nanotopography such as a sphere, a cube, a rod, a disk or
a branched structure, and may be a mixture of particles of various
shapes.
In an embodiment, the inorganic nanomaterial is a quantum dot
material having a very narrow, monodisperse size distribution,
i.e., the size difference between the particles is very small.
Further, the root mean square deviation in the size of the
monodisperse quantum dots is less than 15% rms; still further, the
root mean square deviation in the size of the monodisperse quantum
dots is less than 10% rms; even further, the root mean square
deviation in the size of the monodisperse quantum dots is less than
5% rms.
In an embodiment, the inorganic nanomaterial is a light-emitting
material.
In an embodiment, the light-emitting inorganic nanomaterial is a
quantum dot light-emitting material.
Light-emitting quantum dots can emit light at wavelengths between
380 nanometers and 2500 nanometers. For example, the quantum dots
with CdS cores have an emission wavelength in the range of about
400 nm to 560 nm; the quantum dots with CdSe cores have an emission
wavelength in the range of about 490 nm to 620 nm; the quantum dots
with CdTe cores have an emission wavelength in the range of about
620 nm to 680 nm; the quantum dots with InGaP cores have emission
wavelengths in the range of about 600 nanometers to 700 nanometers;
the quantum dots with PbS cores have emission wavelengths in the
range of about 800 nanometers to 2500 nanometers; the quantums with
PbSe cores have emission wavelength in the range of about 1200 nm
to 2500 nm; the quantums with CuInGaS cores have emission
wavelength in the range of about 600 nm to 680 nm; the quantums
with ZnCuInGaS cores have emission wavelength in the range of about
500 nm to 620 nm; the quantums with CuInGaSe cores have emission
wavelength in the range of about 700 nm to 1000 nm.
In an embodiment, the quantum dot materials comprise blue light
having a peak emission wavelength from 450 nm to 460 nm, or a green
light having a peak emission wavelength from 520 nm to 540 nm, or a
red light having a peak emission wavelength from 615 nm to 630 nm,
or mixtures thereof.
The quantum dots contained can be selected from those of particular
chemical formulations, topographical structures, and/or size
dimensions to obtain light that emits a desired wavelength under
electric excitation. The relationship between the luminescent
properties of quantum dots and their chemical formulation,
morphology structure and/or size dimensions can be found in Annual
Review of Material Sci., 2000, 30, 545-610; Optical Materials
Express., 2012, 2, 594-628; Nano Res, 2009, 2, 425-447. The
entirety of the patent documents listed above are hereby
incorporated herein by reference.
The narrow particle size distribution of quantum dots enables
quantum dots to have a narrower luminescence spectrum (J. Am. Chem.
Soc., 1993, 115, 8706; US 20150108405). In addition, depending on
the chemical formulation and structure used, the size of the
quantum dots needs to be adjusted within the above-mentioned size
range to obtain the luminescent properties of the desired
wavelength.
In an embodiment, the light-emitting quantum dots are semiconductor
nanocrystals. In an embodiment, the size of the semiconductor
nanocrystals is in the range of about 2 nanometers to about 15
nanometers. In addition, depending on the chemical formulation and
structure used, the size of the quantum dots needs to be adjusted
within the above-mentioned size range to obtain the luminescent
properties of the desired wavelength.
The semiconductor nanocrystals include at least one semiconductor
material, wherein the semiconductor material may be selected from
binary or multiple semiconductor compounds or mixtures thereof of
Group IV, II-VI, II-V, III-V, III-VI, IV-VI, I-III-VI, II-IV-VI,
II-IV-V of the periodic table.
The semiconductor material may be selected from the group
consisting of group IV semiconductor compounds composed of
elemental Si, Ge, and binary compounds SiC, SiGe; or group II-VI
semiconductor compounds composed of binary compounds including
CdSe, CdTe, and CdO, CdS, CdSe, ZnS, ZnSe, ZnTe, ZnO, HgO, HgS,
HgSe, HgTe, and ternary compounds include CdSeS, CdSeTe, CdSTe,
CdZnS, CdZnSe, CdZnTe, CgHgS, CdHgSe, ZnSeS, ZnSeTe, ZnSTe, HgSeS,
HgSeTe HgSTe, HgZnS, HgSeSe, and quaternary compounds include
CgHgSeS, CdHgSeTe, CgHgSTe, CdZnSeS, CdZnSeTe, HgZnSeTe, HgZnSTe,
CdZnSTe, HgZnSeS; or group III-V semiconductor compounds composed
of binary compounds including AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs,
GaSb, InN, InP, InAs, InSb, and ternary compounds including AlNP,
AlNAs, AlNSb, AlPAs, AlPSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, InNP,
InNAs, InNSb, InPAs, InPSb, and quaternary compounds include
GaAlNAs, GaAlNSb, GaAlPAs, GaInNP, GaInNAs, GaInNSb, GaInPAs,
GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb; or group IV-VI
semiconductors compounds composed of binary compounds including
SnS, SnSe, SnTe, PbSe, PbS, PbTe, and ternary compounds including
SnSeS, SnSeTe, SnSTe, SnPbS, SnPbSe, SnPbTe, PbSTe, PbSeS, PbSeTe,
and quaternary compounds including SnPbSSe, SnPbSeTe, SnPbSTe.
In an embodiment, the light-emitting quantum dots comprise group
II-VI semiconductor materials, particularly are selected from the
group consisting of CdSe, CdS, CdTe, ZnO, ZnSe, ZnS, ZnTe, HgS,
HgSe, HgTe, CdZnSe and any combination thereof. In an embodiment,
the synthesis of CdSe, CdS is relatively mature and these materials
are used as light-emitting quantum dots for visible light.
In another embodiment, the light-emitting quantum dots comprise
group III-V semiconductor materials, further are selected from the
group consisting of InAs, InP, InN, GaN, InSb, InAsP, InGaAs, GaAs,
GaP, GaSb, AlP, AlN, AlAs, AlSb, CdSeTe, ZnCdSe, and any
combination thereof.
In another embodiment, the light-emitting quantum dots comprise
group IV-VI semiconductor material, further are selected from the
group consisting of PbSe, PbTe, PbS, PbSnTe, Tl.sub.2SnTe.sub.5,
and any combination thereof.
In an embodiment, the quantum dot is in a core-shell structure. The
core and the shell respectively include the same or different one
or more semiconductor materials.
The core of the quantum dot may be selected from the group
consisting of a binary or multiple semiconductor compounds or
mixtures thereof of Group IV, II-VI, II-V, III-V, III-VI, IV-VI,
I-III-VI, II-IV-VI, II-IV-V of the periodic table. Specific
examples for the core of the quantum dot comprise: ZnO, ZnS, ZnSe,
ZnTe, CdO, CdS, CdSe, CdTe, MgS, MgSe, GaAs, GaN, GaP, GaSe, GaSb,
HgO, HgS, HgSe, HgTe, InAs, InN, InSb, AlAs, AlN, AlP, AlSb, PbO,
PbS, PbSe, PbTe, Ge, Si, and an alloy or mixture of any combination
thereof.
The shell of the quantum dot contains a semiconductor material that
is the same as or different from the core. The semiconductor
materials that can be used for the shell include binary or multiple
semiconductor compounds or mixtures thereof of Group IV, II-VI,
II-V, III-V, III-VI, IV-VI, I-III-VI, II-IV-VI, II-IV-V of the
periodic table. Specific examples for the core of the quantum dot
comprise: ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, MgS, MgSe,
GaAs, GaN, GaP, GaSe, GaSb, HgO, HgS, HgSe, HgTe, InAs, InN, InSb,
AlAs, AlN, AlP, AlSb, PbO, PbS, PbSe, PbTe, Ge, Si, and an alloy or
mixture of any combination thereof.
In a quantum dot with a core-shell structure, the shell may include
a monolayer or a multilayer structure. The shell includes one or
more semiconductor materials that are the same or different from
the core. In an embodiment, two or more shells are comprised on the
surface of a quantum dot core. In an embodiment, the shell has a
thickness from about 1 to 20 layers. In a further embodiment, the
shell has a thickness from about 5 to 10 layers.
In an embodiment, the semiconductor material used for the shell has
a larger bandgap than the core. Preferably, the core and the shell
has a structure with type I semiconductor heterojunction.
In another embodiment, the semiconductor material used for the
shell has a smaller bandgap than the core.
In an embodiment, the semiconductor material used for the shell has
an atomic crystal structure that is the same as or similar to that
of the core. Such selection is beneficial to reduced the stress
between the core and shell, making the quantum dots more
stable.
Examples of light-emitting quantum dots using suitable core-shell
structures are (but not limited to):
red light: CdSe/CdS, CdSe/CdS/ZnS, CdSe/CdZnS, etc.
green light: CdZnSe/CdZnS, CdSe/ZnS, etc.
blue light: CdS/CdZnS, CdZnS/ZnS, etc.
In an embodiment, the method for preparing the quantum dots is a
gelatinous growth method. In an embodiment, the method for
preparing monodisperse quantum dots is selected from hot-inject
and/or heating-up. The preparation method is contained in the
document Nano Res, 2009, 2, 425-447; Chem. Mater., 2015, 27 (7), pp
2246-2285. The entirety of the documents listed above are hereby
incorporated herein by reference.
In an embodiment, an organic ligand is comprised on the surface of
the quantum dot. The organic ligands can control the growth process
of quantum dots, regulate the appearance of quantum dots and reduce
surface defects of quantum dots to improve the luminous efficiency
and stability of quantum dots. The organic ligand may be selected
from the group consisting of pyridine, pyrimidine, furan, amine,
alkylphosphine, alkylphosphine oxide, alkylphosphonic acid or
alkylphosphinic acid, alkyl mercaptan and the like. Specific
examples of organic ligands include, but are not limited to,
tri-n-octylphosphine, tri-n-octylphosphine oxide,
trihydroxypropylphosphine, tributylphosphine,
tris(dodecyl)phosphine, dibutyl phosphite, tributyl phosphite,
octadecyl phosphite, trilauryl phosphite, tris(dodecyl)phosphite,
triisodecyl phosphite, bis(2-ethylhexyl)phosphate,
tris(tridecyl)phosphate, hexadecylamine, oleylamine,
octadecylamine, bisoctadecylamine, trioctadecylamine,
bis(2-ethylhexyl)amine, octylamine, dioctylamine, trioctylamine,
dodecylamine, bisdodecylamine, tridodecylamine, hexadecylamine,
phenylphosphoric acid, hexylphosphoric acid, tetradecylphosphoric
acid, octylphosphoric acid, n-octadecylphosphoric acid, propylene
diphosphate, dioctyl ether, diphenyl ether, octyl mercaptan or
dodecyl mercaptan.
In another embodiment, an inorganic ligand is comprised on the
surface of the quantum dot. Quantum dots protected by the inorganic
ligands can be obtained by ligand exchange of organic ligands on
the surface of quantum dots. Examples of specific inorganic ligands
include, but are not limited to: S.sup.2-, HS.sup.-, Se.sup.2-,
HSe.sup.-, Te.sup.2-, HTe.sup.-, TeS.sub.3.sup.2-, OH.sup.-,
NH.sub.2.sup.-, PO.sub.4.sup.3-, MoO.sub.4.sup.2-, and so on.
Examples of such inorganic ligand quantum dots can be found in J.
Am. Chem. Soc. 2011, 133, 10612-10620; ACS Nano, 2014, 9,
9388-9402. The entirety of the documents listed above are hereby
incorporated herein by reference.
In some embodiments, one or more of the same or different ligands
are present on the surface of the quantum dot.
In an embodiment, the luminescence spectrum exhibited by the
monodisperse quantum dots has a symmetrical peak shape and a narrow
peak width at half height. In general, the better the
monodispersity of quantum dots is, the more symmetric the
luminescence peak is and the narrower the peak width at half height
is. Particularly, the quantum dots have a peak width at half height
of light emission of less than 70 nanometers; further, the quantum
dots have a peak width at half height of light emission of less
than 40 nanometers; still further, the quantum dots have a peak
width at half height of light emission of less than 30
nanometers.
In an embodiment, the quantum dots have a luminescence quantum
efficiency of greater than 10%; in an embodiment, the quantum dots
have a luminescence quantum efficiency of greater than 50%; in an
embodiment, the quantum dots have a luminescence quantum efficiency
of greater than 60%; in an embodiment, the quantum dots have a
luminescence quantum efficiency of greater than 70%.
Other materials, techniques, methods, applications and other
information related to quantum dots useful for the present
disclosure are described in the following patent documents:
WO2007/117698, WO2007/120877, WO2008/108798, WO2008/105792,
WO2008/111947, WO2007/092606, WO2007/117672, WO2008/033388,
WO2008/085210, WO2008/13366, WO2008/063652, WO2008/063653,
WO2007/143197, WO2008/070028, WO2008/063653, U.S. Pat. Nos.
6,207,229, 6,251,303, 6,319,426, 6,426,513, 6,576,291, 6,607,829,
6,861,155, 6,921,496, 7,060,243, 7,125,605, 7,138,098, 7,150,910,
7,470,379, 7,566,476, WO2006134599A1. The entirety of the patent
documents listed above are hereby incorporated herein by
reference.
In another embodiment, the light-emitting semiconductor
nanocrystals are nanorods. The properties of the nanorods are
different from those of spherical nanocrystals. For example, the
luminescence of nanorods is polarized along the long rod axis,
while the luminescence of spherical grains is unpolarized (see
Woggon et al, Nano Lett., 2003, 3, p 509). Nanorods have excellent
optical gain characteristics that make them useful as a laser gain
material (see Banin et al. Adv. Mater. 2002, 14, p 317). In
addition, the luminescence of the nanorods can be reversibly turned
on and off under the control of an external electric field (see
Banin et al., Nano Lett. 2005, 5, p 1581). These characteristics of
the nanorods can be preferentially incorporated into the device of
the present disclosure under some circumstances. Examples of the
preparation of the semiconductor nanorods are disclosed in
WO03097904A1, US2008188063A1, US2009053522A1, and KR20050121443A.
The entirety of the patent documents listed above are hereby
incorporated herein by reference.
In another embodiment, in the formulation according to the
disclosure, the inorganic nanomaterial is perovskite nanoparticle
material, in particular light-emitting perovskite nanoparticle
material.
The perovskite nanoparticle material has the general structural
formula of AMX.sub.3, wherein A may be selected from an organic
amine or an alkali metal cation, M may be selected from a metal
cation, and X may be selected from an oxygen or a halogen anion.
Specific examples include, but are not limited to CsPbCl.sub.3,
CsPb(Cl/Br).sub.3, CsPbBr.sub.3, CsPb(I/Br).sub.3, CsPbI.sub.3,
CH.sub.3NH.sub.3PbCl.sub.3, CH.sub.3NH.sub.3Pb(Cl/Br).sub.3,
CH.sub.3NH.sub.3PbBr.sub.3, CH.sub.3NH.sub.3Pb(I/Br).sub.3,
CH.sub.3NH.sub.3PbI.sub.3, and the like. The literatures on
perovskite nanoparticle materials comprise Nano Lett., 2015, 15,
3692-3696; ACS Nano, 2015, 9, 4533-4542; Angewandte Chemie, 2015,
127(19): 5785-5788; Nano Lett., 2015, 15 (4), pp 2640-2644; Adv.
Optical Mater. 2014, 2, 670-678; The Journal of Physical Chemistry
Letters, 2015, 6(3): 446-450; J. Mater. Chem. A, 2015, 3,
9187-9193; Inorg. Chem. 2015, 54, 740-745; RSC Adv., 2014, 4,
55908-55911; J. Am. Chem. Soc., 2014, 136 (3), pp 850-853; Part.
Part. Syst. Charact. 2015, doi: 10.1002/ppsc.201400214; Nanoscale,
2013, 5(19): 8752-8780. The entirety of the patent documents listed
above are hereby incorporated herein by reference.
In another embodiment, in the formulation according to the
disclosure, the inorganic nanomaterial is a metal nanoparticle
material, particularly a light-emitting metal nanoparticle
material.
The metal nanoparticles include, but are not limited to,
nanoparticles of chromium (Cr), molybdenum (Mo), tungsten (W),
ruthenium (Ru), rhodium (Rh), nickel (Ni), silver (Ag), copper
(Cu), zinc (Zn), palladium (Pd), gold (Au), osmium (Os), rhenium
(Re), iridium (Ir), and platinum (Pt). The types, morphologies and
synthetic methods of common metal nanoparticles can be found in
Angew. Chem. Int. Ed. 2009, 48, 60-103; Angew. Chem. Int. Ed. 2012,
51, 7656-7673; Adv. Mater. 2003, 15, No. 5, 353-389; Adv. Mater.
2010, 22, 1781-1804; Small. 2008, 3, 310-325; Angew. Chem. Int. Ed.
2008, 47, 2-46 and the like, and the literatures cited therein. The
entirety of the patent documents listed above are hereby
incorporated herein by reference.
In another embodiment, the inorganic nanomaterial has charge
transporting property.
In an embodiment, the inorganic nanomaterial has electron
transporting capability. Further, such an inorganic nanomaterial is
selected from n-type semiconductor materials. Examples of n-type
inorganic semiconductor materials include, but are not limited to,
metal chalcogen compounds, metal phosphorus family compounds, or
elemental semiconductors, such as metal oxides, metal sulfides,
metal selenides, metal tellurides, metal nitrides, metal phosphide,
or metal arsenide. The preferred n-type inorganic semiconductor
material is selected from the group consisting of ZnO, ZnS, ZnSe,
TiO.sub.2, ZnTe, GaN, GaP, AlN, CdSe, CdS, CdTe, CdZnSe, and any
combination thereof.
In some embodiments, the inorganic nanomaterial has a hole
transporting capability. Further, such inorganic nanomaterials are
selected from p-type semiconductor materials. The inorganic p-type
semiconductor material may be selected from the group consisting of
NiOx, WOx, MoOx, RuOx, VOx, CuOx, and any combination thereof.
In an embodiment, a printing ink formulation comprises at least two
or more inorganic nanomaterials.
In another embodiment, a formulation comprises at least one organic
functional material.
The organic functional materials comprise the hole (also known as
electronic hole) injection or the transport materials (HIM/HTM),
the hole blocking materials (HBM), the electron injection or
transport materials (EIM/ETM), the electron blocking materials
(EBM), the organic host materials, the singlet emitters
(fluorescent emitters), the thermal activated delayed fluorescent
material (TADF) and the triplet emitters (phosphorescence
emitters), particularly the luminescent organometallic complexes
and the organic dyes. Various organic functional materials are
described in detail, for example, in WO2010135519A1,
US20090134784A1, and WO2011110277A1, the entire contents of which
are hereby incorporated herein by reference.
In an embodiment, the organic functional material has a solubility
in the above solvent of at least 0.2 wt %;
In an embodiment, the organic functional material has a solubility
in the above solvent of at least 0.3 wt %;
In an embodiment, the organic functional material has a solubility
in the above solvent of at least 0.6 wt %;
In an embodiment, the organic functional material has a solubility
in the above solvent of at least 1.0 wt %;
In an embodiment, the organic functional material has a solubility
in the above solvent of at least 1.5 wt %.
The organic functional material may be a small molecule material or
a high polymer material. In the present disclosure, the small
molecule organic material means a material having a molecular
weight of at most 4000 g/mol, and a material having a molecular
weight higher than 4000 g/mol is collectively referred to as a high
polymer.
In an embodiment, the functional material comprised in a printing
ink formulation is an organic small molecule material.
In an embodiment, the organic functional material in a printing ink
formulation comprises at least one host material and at least one
emitter.
In an embodiment, the organic functional material in a printing ink
formulation comprises a host material and a singlet emitter.
In another embodiment, the organic functional material in a
printing ink formulation comprises a host material and a triplet
emitter.
In another embodiment, the organic functional material in a
printing ink formulation comprises a host material and a thermal
activated delayed fluorescent material.
In other embodiments, the organic functional material in a printing
ink formulation comprises a hole transport material (HTM).
In other embodiments, the organic functional material in a printing
ink formulation comprises a hole transport material (HTM), and the
HTM comprising a crosslinkable group.
The organic small molecule functional materials described in the
appropriate preferred embodiments will be described in some detail
below (but are not limited thereto).
1. HIM/HTM/EBM
Suitable organic HIM/HTM materials may be selected from the
compounds containing the following structural units:
phthalocyanine, porphyrin, amine, aromatic amine, biphenyl
triarylamine, thiophene, fused thiophene such as dithienothiophene
and bithiophene, pyrrole, aniline, carbazole, indolocarbazole, and
derivatives thereof. In addition, suitable HIMs also include
fluorocarbon-containing polymers, conductivity-doped polymers,
conductive polymers such as PEDOT:PSS.
The electron blocking layer (EBL) is used to block electrons from
the adjacent functional layers, particularly the light emitting
layers. The presence of the EBL generally leads to an increase in
luminous efficiency, comparing to a light emitting device without
the blocking layer. The electron blocking material (EBM) of the
electron blocking layer (EBL) requires a higher LUMO than the
adjacent functional layer such as light emitting layer.
In an embodiment, EBM has a larger excited state energy level such
as singlet state or triplet state than the adjacent light emitting
layer, depending on the emitter; at the same time, the EBM has a
hole transport function. Generally, HIM/HTM materials, which have
high LUMO energy level, can be used as EBM.
Examples of derivative compounds of cyclic aromatic amines that can
be used as HIM, HTM, or EBM, include but are not limited to the
following general structures:
##STR00057##
Each of Ar.sup.1 to Ar.sup.9 may be independently selected from the
group consisting of cyclic aromatic hydrocarbon compound such as
benzene, biphenyl, triphenyl, benzo, naphthalene, anthracene,
phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene,
azulene; and aromatic heterocycle compound such as
dibenzothiophene, dibenzofuran, furan, thiophene, benzofuran,
benzothiophene, carbazole, pyrazole, imidazole, triazole,
isoxazole, thiazole, oxadiazole, oxytriazole, dioxazole,
thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine,
oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole,
indolizine, benzoxazole, benzisoxazole, benzothiazole, quinoline,
isoquinoline, cinnoline, quinazoline, quinoxaline, naphthalene,
phthalein, pteridine, xanthene, acridine, phenazine, phenothiazine,
phenoxazine, dibenzoselenophene, benzoselenophene,
benzofuropyridine, indolocarbazole, pyridylindole,
pyrrolodipyridine, furodipyridine, benzothieopyridine,
thienopyridine, benzoselenophenepyridine and selenophenodipyridine;
and groups containing 2 to 10 ring structures, which may be the
same or different types of cyclic aromatic hydrocarbyl groups or
aromatic heterocyclic groups, and linked to each other directly or
through at least one of the following groups: such as oxygen atom,
nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron
atom, chain structure unit, and aliphatic ring group. Wherein, each
Ar may be further substituted, the substituent may be selected from
the group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl,
alkynyl, aralkyl, heteroalkyl, aryl and heteroaryl.
In one aspect, Ar.sup.1 to Ar.sup.9 can be independently selected
from the group comprising:
##STR00058##
n is an integer from 1 to 20; X.sup.1 to X.sup.8 is CH or N;
Ar.sup.1 is as defined above.
Additional examples of cyclic aromatic amine-derived compounds can
be seen in U.S. Pat. Nos. 3,567,450, 4,720,432, 5,061,569,
3,615,404 and 5,061,569.
Examples of metal clathrate that can be used as HTM or HIM include
but are not limited to the following general structures:
##STR00059##
wherein M is a metal with an atomic weight greater than 40;
(Y.sup.1-Y.sup.2) is a bidentate ligand, Y.sup.1 and Y.sup.2 are
independently selected from the group consisting of C, N, O, P and
S; L is an auxiliary ligand; m is an integer whose value is from 1
to the maximum coordination number of this metal; m+n is the
maximum coordination number of this metal.
In an embodiment, (Y.sup.1-Y.sup.2) is 2-phenylpyridine
derivative.
In another embodiment, (Y.sup.1-Y.sup.2) is a carbene ligand.
In another embodiment, M is selected from Ir, Pt, Os, and Zn.
In another aspect, the metal complex has a HOMO greater than -5.5
eV (relative to vacuum level).
In an embodiment, a compound selected from any of the following
compounds is used as a compound of HIM/HTM:
##STR00060## ##STR00061##
2. Triplet Host Material
The example of a triplet host material is not particularly limited,
and any metal complex or organic compound may be used as a host
material as long as its triplet energy is higher than that of a
light emitter, particularly a triplet light emitter or a
phosphorescent light emitter. An example of metal complex that can
be used as a triplet host includes, but are not limited to, the
following general structures:
##STR00062##
wherein M is a metal; (Y.sup.3-Y.sup.4) is a bidentate ligand,
Y.sup.3 and Y.sup.4 are independently selected from C, N, O, P or
S; L is an auxiliary ligand; m is an integer whose value is from 1
to the maximum coordination number of this metal; m+n is the
maximum coordination number of this metal.
In an embodiment, the metal complex that can be used as the triplet
host is in the following form:
##STR00063##
wherein, (O--N) is a bidentate ligand in which the metal is
coordinated with O and N atoms.
In one of the embodiments, M is selected from Ir or Pt.
Examples of organic compounds that can be used as a triplet host
are selected from the group consisting of cyclic aromatic compound
such as benzene, biphenyl, triphenyl, benzo, fluorene; and a
compound containing an aromatic heterocyclic group such as
dibenzothiophene, dibenzofuran, dibenzoselenophen, furan,
thiophene, benzofuran, benzothiophene, benzoselenophen, carbazole,
indolocarbazole, pyridine indole, pyrrole dipyridine, pyrazole,
imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole,
dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine,
triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole,
indazole, oxazole, dibenzoxazole, benzisoxazole, benzothiazole,
quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline,
naphthalene, phthalein, pteridine, xanthene, acridine, phenazine,
phenothiazine, phenoxazine, benzofuropyridine, furopyridine,
benzothiophene pyridine, thiophene pyridine,
benzoselenophenepyridine and selenophenodipyridine; and a group
containing 2 to 10 ring structures which may be the same or
different types of cyclic aromatic or aromatic heterocyclic groups,
and linked each other directly or through at least one the
following groups: an oxygen atom, a nitrogen atom, a sulfur atom, a
silicon atom, a phosphorus atom, a boron atom, a chain structure
unit, and an aliphatic ring group. Wherein, each compound may be
further substituted, the substituent may be selected from the group
consisting of hydrogen, alkyl, alkoxy, amino, alkenyl, alkynyl,
aralkyl, heteroalkyl, aryl and heteroaryl.
In an embodiment, the triplet host material may be selected from
compounds comprising at least one of the following groups:
##STR00064## ##STR00065##
wherein R.sup.1 to R.sup.7 are mutually independently selected from
the group consisting of hydrogen, alkyl, alkoxy, amino, alkene,
alkyne, aralkyl, heteroalkyl, aryl or heteroaryl. R.sup.1 to
R.sup.7 have the same meaning as Ar.sup.t and Ar.sup.2 described
above when R.sup.1 to R.sup.7 are aryl or heteroaryl; n is an
integer from 0 to 20; X.sup.1 to X.sup.8 is selected from CH or N;
X.sup.9 is selected from CR.sup.1R.sup.2 or NR.sup.1.
In an embodiment, the triplet host material is selected from the
following compounds:
##STR00066##
3. Singlet Host Material:
The example of the singlet host material is not particularly
limited, any organic compound can be used as the host as long as
its singlet energy is higher than that of the emitter, particularly
that of the singlet emitter or the fluorescent emitter.
Examples of organic compounds used as singlet host material are
selected from the group consisting of: cyclic aromatic hydrocarbon
compounds such as benzene, biphenyl, triphenyl, benzo, naphthalene,
anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene,
perylene, azulene; and aromatic heterocycles compounds such as
dibenzothiophene, dibenzofuran, dibenzoselenophene, furan,
thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole,
indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole,
imidazole, triazole, isoxazole, thiazole, oxadiazole, oxytriazole,
dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine,
triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole,
indazole, indolizine, benzoxazole, benzoxazole, benzothiazole,
quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline,
naphthalene, phthalein, pteridine, xanthene, acridine, phenazine,
phenothiazine, phenoxazine, benzofuropyridine, furan dipyridine,
benzothiophene pyridine, thiophenyldipyridine,
benzoselenophenepyridine and selenophenodipyridine; and groups
containing 2 to 10 ring structures, which may be the same or
different types of cyclic aromatic hydrocarbyl groups or aromatic
heterocyclic groups, and linked to each other directly or through
at least one of the following groups: oxygen atom, nitrogen atom,
sulfur atom, silicon atom, phosphorus atom, boron atom, chain
structure unit, and aliphatic ring group.
In an embodiment, the singlet host material may be selected from
compounds comprising at least one of the following groups:
##STR00067## ##STR00068##
wherein R.sup.1 may be independently selected from the group
consisting of hydrogen, alkyl, alkoxy, amino, alkene, alkynyl,
aralkyl, heteroalkyl, aryl and heteroaryl; Ar.sup.1 is aryl or
heteroaryl, and has the same meaning as Ar.sup.1 defined in the
above HTM; n is an integer from 0 to 20; X.sup.1 to X.sup.8 is
selected from CH or N; X.sup.9 and X.sup.10 is selected from
CR.sup.1R.sup.2 or NR.sup.1.
In an embodiment, the fluorenyl singlet host material is selected
from the following compounds:
##STR00069##
4. Singlet Emitter
The singlet emitter usually has longer conjugated 21 electron
system. To date, there have been many examples, such as,
styrylamine and derivatives thereof disclosed in JP2913116B and
WO2001021729A1, and indenofluorene and derivatives thereof
disclosed in WO2008/006449 and WO2007/140847.
In an embodiment, the singlet emitter can be selected from
mono-styrylamine, di-styrylamine,tri-styrylamine,
tetra-styrylamine, styryl phosphine, styryl ether, or
arylamine.
A mono-styrylamine is a compound comprising an unsubstituted or
substituted styryl group and at least one amine, particularly an
aromatic amine. A di-styrylamine is a compound comprising two
unsubstituted or substituted styryl groups and at least one amine,
particularly an aromatic amine. A tri-styrylamine is a compound
comprising three unsubstituted or substituted styryl groups and at
least one amine, particularly an aromatic amine. A
tetra-styrylamine is a compound comprising four unsubstituted or
substituted styryl groups and at least one amine, particularly an
aromatic amine. A particularly d styrene is stilbene, which may be
further substituted. The definitions of the corresponding
phosphines and ethers are similar to those of amines. An aryl amine
or aromatic amine refers to a compound comprising three
unsubstituted or substituted aromatic ring or heterocyclic systems
directly coupled to nitrogen. In an embodiment, at least one of
these aromatic or heterocyclic ring systems has fused ring systems,
and the fused system particularly has at least 14 aromatic ring
atoms. Wherein, examples in an embodiment are aromatic anthramine,
aromatic anthradiamine, aromatic pyrenamine, aromatic
pyrenediamine, aromatic chryseneamine or aromatic chrysenediamine.
An aromatic anthramine refers to a compound in which a diarylamino
group is directly coupled to anthracene, particularly at position
9. An aromatic anthradiamine refers to a compound in which two
diarylamino groups are directly coupled to anthracene, particularly
at positions 9, 10. Aromatic pyrene amine, aromatic pyrene diamine,
aromatic chrysene amine and aromatic chrysene diamine are similarly
defined, wherein the diarylarylamino group is particularly attached
to position 1 or 1 and 6 of pyrene.
The examples of singlet emitter based on vinylamine and arylamine
can be found in the following patent documents: WO 2006/000388, WO
2006/058737, WO 2006/000389, WO 2007/065549, WO 2007/115610, U.S.
Pat. No. 7,250,532 B2, DE 102005058557 A1, CN 1583691 A, JP
08053397 A, U.S. Pat. No. 6,251,531 B1, US 2006/210830 A, EP 1 957
606 A1 and US 2008/0113101 A1, the entirety of the patent documents
listed above are hereby incorporated herein by reference.
Examples of singlet emitters based on distyrylbenzene and
derivatives thereof may be found in U.S. Pat. No. 5,121,029.
Further, singlet emitters may be selected from the group consisting
of: indenofluorene-amine and indenofluorene-diamine disclosed in WO
2006/122630, benzoindenofluorene-amine and
benzoindenofluorene-diamine disclosed in WO 2008/006449,
dibenzoindenofluorene-amine and dibenzoindenofluorene-diamine
disclosed in WO2007/140847.
Other materials that may be used as singlet emitters are polycyclic
aromatic hydrocarbon compounds, particularly the derivatives of the
following compounds: anthracene such as
9,10-di(2-naphthanthracene), naphthalene, tetracene, xanthene,
phenanthrene, pyrene (such as 2,5,8,11-tetra-t-butylperylene),
indenopyrene, phenylene (such as 4,4'-bis
(9-ethyl-3-carbazovinylene)-1,1'-biphenyl), periflanthene,
decacyclene, coronene, fluorene, spirobifluorene, arylpyrene (e.g.,
US20060222886), arylenevinylene (e.g., U.S. Pat. Nos. 5,121,029,
5,130,603), cyclopentadiene such as tetraphenylcyclopentadiene,
rubrene, coumarine, rhodamine, quinacridone, pyrane such as
4(dicyanomethylene)-6-(4-dimethylaminostyryl-2-methyl)-4H-pyrane
(DCM), thiapyran, bis (azinyl) imine-boron compound (US
2007/0092753 A1), bis (azinyl) methene compound, carbostyryl
compound, oxazone, benzoxazole, benzothiazole, benzimidazole and
diketopyrrolopyrrole. Examples of singlet emitter materials can be
found in the following patent documents: US 20070252517 A1, U.S.
Pat. Nos. 4,769,292, 6,020,078, US 2007/0252517 A1, US 2007/0252517
A1. The entirety of the patent documents listed above are hereby
incorporated herein by reference.
In an embodiment, the singlet emitter is selected from the
following compounds:
##STR00070##
5. Thermally Activated Delayed Fluorescent Material (TADF):
A traditional organic fluorescent material can only emit light
using 25% singlet exciton emission formed by electric excitation,
and the device has a low internal quantum efficiency (up to 25%).
Although the phosphorescent material enhances the intersystem
crossing due to the strong spin-orbit coupling of the heavy atom
center, the singlet exciton and the triplet exciton emission formed
by the electric excitation can be effectively utilized, so that the
internal quantum efficiency of the device can reach 100%. However,
the application of phosphorescent material in OLEDs is limited by
the problems such as high cost, poor material stability and serious
roll-off of the device efficiency, etc. The thermally activated
delayed fluorescent material is the third generation of organic
light-emitting material developed after the organic fluorescent
material and the organic phosphorescent material. This type of
material generally has a small singlet-triplet excited state energy
level difference (.DELTA.Est), and triplet excitons can be
converted to singlet excitons by intersystem crossing, which can
fully use singlet excitons and triplet excitons formed under
electric excitation. The device can achieve 100% internal quantum
efficiency.
TADF materials need to have a small singlet-triplet energy level
difference (.DELTA.Est). In an embodiment, .DELTA.Est<0.3 eV; in
an embodiment, .DELTA.Est<0.2 eV; in an embodiment,
.DELTA.Est<0.1 eV; in an embodiment, .DELTA.Est<0.05 eV. In
an embodiment, the TADF has better fluorescence quantum efficiency.
Some TADF materials can be found in the following patent documents:
CN103483332(A), TW201309696(A), TW201309778(A), TW201343874(A),
TW201350558(A), US20120217869(A1), WO2013133359(A1),
WO2013154064(A1), Adachi, et. al. Adv. Mater., 21, 2009, 4802,
Adachi, et. al. Appl. Phys. Lett., 98, 2011, 083302, Adachi, et.
al. Appl. Phys. Lett., 101, 2012, 093306, Adachi, et. al. Chem.
Commun., 48, 2012, 11392, Adachi, et. al. Nature Photonics, 6,
2012, 253, Adachi, et. al. Nature, 492, 2012, 234, Adachi, et. al.
J. Am. Chem. Soc, 134, 2012, 14706, Adachi, et. al. Angew. Chem.
Int. Ed, 51, 2012, 11311, Adachi, et. al. Chem. Commun., 48, 2012,
9580, Adachi, et. al. Chem. Commun., 48, 2013, 10385, Adachi, et.
al. Adv. Mater., 25, 2013, 3319, Adachi, et. al. Adv. Mater., 25,
2013, 3707, Adachi, et. al. Chem. Mater., 25, 2013, 3038, Adachi,
et. al. Chem. Mater., 25, 2013, 3766, Adachi, et. al. J. Mater.
Chem. C., 1, 2013, 4599, Adachi, et. al. J. Phys. Chem. A., 117,
2013, 5607. The entirety of the contents of the patents or article
documents listed above are hereby incorporated herein by
reference.
In an embodiment, the TADF material is selected from the following
compounds:
##STR00071## ##STR00072## ##STR00073## ##STR00074## ##STR00075##
##STR00076## ##STR00077## ##STR00078##
6. Triplet Emitter
The triplet emitter is also called phosphorescent material. In an
embodiment, the triplet emitter is a metal complex containing a
formula M(L)n. M is a metal atom, and each occurrence of L may be
the same or different and is an organic ligand which is bonded or
coordinated to the metal atom M through one or more positions; n is
an integer greater than 1, particularly 1, 2, 3, 4, 5 or 6.
Optionally, these metal complexes are attached to a polymer through
one or more positions, especially through organic ligands.
In an embodiment, the metal atom M is selected from a transitional
metal element, a lanthanoid element or a lanthanoid element,
further selected from Ir, Pt, Pd, Au, Rh, Ru, Os, Sm, Eu, Gd, Tb,
Dy, Re, Cu or Ag, still further selected from Os, Ir, Ru, Rh, Re,
Pd, or Pt.
In an embodiment, the triplet emitter contains a chelating ligand
(i.e., a ligand) that coordinates with the metal through at least
two binding sites. Particularly, the triplet emitter contains two
or three identical or different bidentate or multidentate ligands.
The chelating ligand is advantageous for improve the stability of
the metal complexes.
In an embodiment, the organic ligand is selected from the group
consisting of phenylpyridine derivatives, 7,8-benzoquinoline
derivatives, 2(2-thienyl) pyridine derivatives, 2(1-naphthyl)
pyridine derivatives, or 2 phenylquinoline derivatives. All of
these organic ligands may be substituted, for example, substituted
by fluoromethyl or trifluoromethyl. Preferably, the ancillary
ligand may be selected from acetone acetate or picric acid.
In an embodiment, the metal clathrates that can be used as triplet
emitters have the following form:
##STR00079##
M is a metal and selected from transition metal elements,
lanthanoid elements, or lanthanoid elements.
Ar.sup.1 is a cyclic group which may be the same or different at
each occurrence, and Ar.sup.1 contains at least one donor atom,
i.e. an atom containing a lone pair of electrons, such as nitrogen
or phosphorus, coordinated to a metal thorough its cyclic group;
Ar.sup.2 is a cyclic group, which may be the same or different at
each occurrence, and Ar.sup.2 contains at least one C atom, which
is linked to the metal through its cyclic group; Ar.sup.1 and
Ar.sup.2 are covalently linked together and may each carry one or
more substituted groups, which may in turn be linked together by a
substituted group; L may be the same or different at each
occurrence, and L is an auxiliary ligand, further a bidentate
chelating ligand, still further a monoanionic bidentate chelate
ligand; m is selected from 1, 2 or 3, further is 2 or 3,
particularly is 3; m is selected from 0, 1 or 2, further is 0 or 1,
particularly is 0.
Examples of triplet emitter materials and examples of applications
thereof can be found in the following patent documents and
references: WO 200070655, WO 200141512, WO 200202714, WO 200215645,
EP 1191613, EP 1191612, EP 1191614, WO 2005033244, WO 2005019373,
US 2005/0258742, WO 2009146770, WO 2010015307, WO 2010031485, WO
2010054731, WO 2010054728, WO 2010086089, WO 2010099852, WO
2010102709, US 20070087219 A1, US 20090061681 A1, US 20010053462
A1, Baldo, Thompson et al. Nature 403, (2000), 750-753, US
20090061681 A1, US 20090061681 A1, Adachi et al. Appl. Phys. Lett.
78 (2001), 1622-1624, J. Kido et al. Appl. Phys. Lett. 65 (1994),
2124, Kido et al. Chem. Lett. 657, 1990, US 2007/0252517 A1,
Johnson et al., JACS 105, 1983, 1795, Wrighton, JACS 96, 1974, 998,
Ma et al., Synth. Metals 94, 1998, 245, U.S. Pat. Nos. 6,824,895,
7,029,766, 6,835,469, 6,830,828, US 20010053462 A1, WO 2007095118
A1, US 2012004407A1, WO 2012007088A1, WO2012007087A1, WO
2012007086A1, US 2008027220A1, WO 2011157339A1, CN 102282150A, WO
2009118087A1. The entire contents of the above listed patent
documents and literatures are hereby incorporated by reference.
In an embodiment, the triplet emitter is selected from the
following compounds:
##STR00080## ##STR00081## ##STR00082## ##STR00083## ##STR00084##
##STR00085## ##STR00086## ##STR00087## ##STR00088##
In an embodiment, the functional material comprised in the
formulation is a polymer material.
The organic small molecule functional materials described above,
including the HIM, the HTM, the ETM, the EIM, the host material,
the fluorescent emitter, the phosphorescent emitter, and the TADF
can all be included as repeating units in the polymer.
In an embodiment, the polymer suitable for the present disclosure
is a conjugated polymer. Generally, conjugated polymers have the
following formula:
##STR00089##
wherein B, A may be independently selected from the same or
different structural units in multiple occurrences
B: a .pi.-conjugated structural unit having a large energy gap,
also called a backbone unit, selected from a monocyclic or
polycyclic aryl or heteroaryl group, and further, the unit form is
benzene, biphenylene, naphthalene, anthracene, phenanthrene,
dihydrophenanthrene, 9,10-dihydrophenanthrene, fluorene,
difluorene, spirobifluorene, phenylenevinylene,
trans-indenofluorenes, cis-indeno, dibenzo-indenofluorene,
indenonaphthalene and a derivative thereof.
A: a .pi.-conjugated structural unit having a less energy gap, also
called a functional unit, selected from the structural units
comprising the above-described hole injection or transport material
(HIM/HTM), electronic injection or transport material (EIM/ETM),
host material, singlet emitter (fluorescent emitter), triplet
emitter (phosphorescent emitter). x, y: >0, and x+y=1;
In an embodiment, the functional material comprised in the
formulation is a polymer HTM.
In an embodiment, the polymer HTM material is a homopolymer,
further is polythiophene, polypyrrole, polyaniline, polybiphenyl
triarylamine, polyvinylcarbazole, and derivatives thereof.
In a particularly embodiment, the polymer HTM material is a
conjugated copolymer represented by Chemical Formula 1, wherein
wherein B, A may be independently selected from the same or
different structural units in multiple occurrences
B: a .pi.-conjugated structural unit having a large energy gap,
also called a backbone unit, selected from a monocyclic or
polycyclic aryl or heteroaryl group, and further, the unit form is
benzene, biphenylene, naphthalene, anthracene, phenanthrene,
dihydrophenanthrene, 9,10-dihydrophenanthrene, fluorene,
difluorene, spirobifluorene, phenylenevinylene,
trans-indenofluorenes, cis-indeno, dibenzo-indenofluorene,
indenonaphthalene and a derivative thereof.
A: a functional group having a hole transporting capability, which
may be identically or differently selected from the structural unit
containing the hole injection or transport material (HIM/HTM)
described above; in a preferred embodiment, A is selected from
amines, biphenyl 5 triarylamine, thiophene, thiophthene such as
dithienothiophene and thiophthene, pyrrole, aniline, carbazole,
indenocarbazole, indolocarbazole, pentacene, phthalocyanine,
porphyrin and derivatives thereof.
x, y: >0, and x+y=1; generally, y.gtoreq.0.10, further
y.gtoreq.0.15, still further y.gtoreq.0.20, even further
x=y=0.5.
In an embodiment, the conjugated polymer as HTM may be selected
from the following compounds:
##STR00090##
wherein,
Rs are each independently selected from the group consisting of:
hydrogen, a linear alkyl containing 1 to 20 C atoms, linear alkoxy
containing 1 to 20 C atoms or linear thioalkoxy group containing 1
to 20 C atoms, or a branched or cyclic alkyl containing 3 to 20 C
atoms, branched or cyclic alkoxy containing 3 to 20 C atoms or
branched or cyclic thioalkoxy group containing 3 to 20 C atoms or
silyl group containing 3 to 20 C atoms, or a substituted ketone
group containing 1 to 20 C atoms, or an alkoxycarbonyl group
containing 2 to 10 C atoms, or an aryloxycarbonyl group containing
7 to 20 C atoms, or a cyano group (--CN), a carbamoyl group
(--C(.dbd.O)NH2), a haloformyl group (--C(.dbd.O)--X wherein X
represents a halogen atom), a formyl group (--C(.dbd.O)--H), an
isocyano group, an isocyanate group, an thiocyanate group or an
isothiocyanate group, an hydroxyl group, an nitro group, an
CF.sub.3 group, Cl, Br, F, a crosslinkable group or a substituted
or unsubstituted aromatic ring system containing 5 to 40 ring atoms
or substituted or unsubstituted heteroaromatic ring system
containing 5 to 40 ring atoms, or an aryloxy group containing 5 to
40 ring atoms or heteroaryloxy group containing 5 to 40 ring atoms,
or a combination of these groups, wherein one or more of the groups
Rs may form a monocyclic or polycyclic aliphatic or aromatic ring
system with each other and/or a ring bonded thereto;
r is 0, 1, 2, 3 or 4;
s is 0, 1, 2, 3, 4 or 5;
x, y: >0, and x+y=1; generally y.gtoreq.0.10, further
y.gtoreq.0.15, still further y.gtoreq.0.20, even further
x=y=0.5.
Another kind of organic functional material is polymers having
electron transporting capability, including conjugated polymers and
non-conjugated polymers.
In an embodiment, the selected polymer ETM material is a
homopolymer, the homopolymer preferably selected from the group
consisting of polyphenanthrene, polyphenanthroline,
polyindenofluorene, polyspirobifluorene, polyfluorene and
derivatives thereof.
In an embodiment, a polymer ETM material is a conjugated copolymer
represented by Chemical Formula 1, wherein A may independently be
selected from the same or different forms in multiple
occurrences:
B: a .pi.-conjugated structural unit having a large energy gap,
also called a backbone unit, selected from a monocyclic or
polycyclic aryl or heteroaryl group, and further, the unit form is
benzene, biphenylene, naphthalene, anthracene, phenanthrene,
dihydrophenanthrene, 9,10-dihydrophenanthrene, fluorene,
difluorene, spirobifluorene, phenylenevinylene,
trans-indenofluorenes, cis-indeno, dibenzo-indenofluorene,
indenonaphthalene and derivatives thereof.
A: a functional group having an electron transporting capability,
further selected from the group consisting of
tris(8-hydroxyquinoline)aluminum (AlQ3), benzene, diphenylene,
naphthalene, anthracene, phenanthrene, dihydrophenanthrene,
fluorene, difluorene, spirobifluorene, phenylenevinylene, pyrene,
perylene, 9,10-dihydrophenanthrene, phenazine, phenanthroline,
trans-indenofluorenes, cis-indeno, dibenzo-indenofluorene,
indenonaphthalene, benzoanthracene and derivatives thereof.
x, y: >0, and x+y=1; generally, y.gtoreq.0.10, further
y.gtoreq.0.15, still further y.gtoreq.0.20, even further
x=y=0.5.
In another embodiment, the functional material comprised in the
formulation according to the disclosure is a light-emitting
polymer.
In an embodiment, the light-emitting polymer is a conjugated
polymer of the formula:
##STR00091##
B: Same as the definition of Chemical Formula 1.
A1: a functional group having a hole or electron transporting
capability, which may be selected from structural units containing
the above-described hole injection or transport material (HIM/HTM),
or electron injection or transport material (EIM/ETM).
A2: a group having a light-emitting function, which may be selected
from structural units containing the above-described singlet light
emitter (fluorescent emitter) and heavy light emitter
(phosphorescent emitter).
x, y, z: >0, and x+y+z=1;
Examples of light emitting polymers are disclosed in the following
patent applications: WO2007043495, WO2006118345, WO2006114364,
WO2006062226, WO2006052457, WO2005104264, WO2005056633,
WO2005033174, WO2004113412, WO2004041901, WO2003099901,
WO2003051092, WO2003020790, WO2003020790, US2020040076853,
US2020040002576, US2007208567, US2005962631, EP 201345477,
EP2001344788, DE102004020298. The entirety of the contents of the
patent documents listed above are hereby incorporated herein by
reference.
In another embodiment, the polymer suitable for the present
disclosure is a non-conjugated polymer. This can be a polymer in
which all of the functional groups are on the side chain and the
backbone is non-conjugated. Some of such non-conjugated high
polymers useful as phosphorescent host or phosphorescent
light-emitting materials are disclosed in U.S. Pat. No. 7,250,226
B2, JP2007059939A, JP2007211243A2 and JP2007197574A2, and some
useful as fluorescent light-emitting materials are disclosed in
JP2005108556, JP2005285661, and JP2003338375. Alternatively, the
non-conjugated high polymer may be a polymer in which the
functional units conjugated to the main chain are linked by
non-conjugated linking units. Examples of such high polymers are
disclosed in DE102009023154.4 and DE102009023156.0. The entirety of
the above patent documents are hereby incorporated herein by
reference.
The present disclosure also relates to a method for forming the
above-described printing ink formulation into a functional material
film on a substrate, comprising the steps of:
applying a formulation to the substrate using a method of printing
or coating; evaporating a solvent in the printing ink
formulation.
That is, the present disclosure relates to a method for preparing a
thin film comprising a functional material using a method of
printing or coating.
The printing or coating method in which any of the formulations as
described above is applied to a substrate by printing or coating
may be selected from inkjet printing, nozzle printing, typography,
screen printing, dip coating, spin coating, blade coating, roller
printing, twist roller printing, lithography, flexography, rotary
printing, spray coating, brush coating or transfer printing, or
slot die coating, and the like.
In an embodiment, the film comprising the functional material is
prepared using a method of inkjet printing. Inkjet printers that
can be used to print inks in accordance with the present disclosure
are commercially available printers and include drop-on-demand
printheads. These printers are available from Fujifilm Dimatix
(Lebanon, N.H.), Trident International (Brookfield, Conn.), Epson
(Torrance, Calif.), Hitachi Data systems Corporation (Santa Clara,
Calif.), Xaar PLC (Cambridge, United Kingdom), and Idanit
Technologies, Limited (Rishon Le Zion, Isreal). For example, the
present disclosure can be printed using Dimatix Materials Printer
DMP-3000 (Fujifilm).
The disclosure further relates to an electronic device comprising a
functional layer, which is a functional material film formed with
the printing ink formulation described above. In addition, the
electronic device may comprise one or more functional layers, that
is, may comprise one or more layers of functional material film,
the functional layers may be prepared by printing or coating
method.
Suitable electronic devices include an quantum dot light-emitting
diode (QLED), an quantum dot photovoltage (QPV), an quantum dot
light-emitting electrochemical cell (QLEEC), an quantum dot
field-effect transistor (QFET), an quantum dot light-emitting
field-effect transistor, an quantum dot laser, an quantum dot
sensor, an organic light-emitting diode (OLED), an organic
photovoltage cell (OPV), an organic light-emitting electrochemical
cell (OLEEC), an organic field-effect transistor (OFET), an organic
light-emitting field-effect transistor, an organic laser, an
organic sensor.
The FIGURE is a schematic diagram of an electronic device in an
embodiment. The electronic device is an electroluminescent device
or a photovoltaic cell, as shown in the FIGURE, comprising a
substrate 101, an anode 102, at least one light emitting layer or a
light absorption layer 104, and a cathode 106. The following
description is only for the electroluminescent device.
The substrate 101 may be opaque or transparent. A transparent
substrate can be used to fabricate a transparent light-emitting
device. For example, see Bulovic et al. Nature 1996, 380, p 29 and
Gu et al. Appl. Phys. Lett. 1996, 68, p 2606. The substrate may be
rigid or elastic. The substrate may be plastic, metal, a
semiconductor wafer or glass. Especially the substrate has a smooth
surface. The substrate without any surface defects is a particular
desirable choice. In an embodiment, the substrate may be selected
from polymer thin film or plastic which have the glass transition
temperature Tg larger than 150.degree. C., further larger than
200.degree. C., still further larger than 250.degree. C., even
further larger than 300.degree. C. Suitable examples of the
substrate are poly(ethylene terephthalate) (PET) and
polyethylene(2,6-naphthalate) (PEN).
The anode 102 may comprise a conductive metal or a metal oxide, or
a conductive polymer. The anode can easily inject holes into the
HIL or HTL or the light emitting layer. In an embodiment, the
absolute value of the difference between the work function of the
anode and the HOMO energy level or the valence band energy level of
the p-type semiconductor material as the HIL or HTL is less than
0.5 eV, further less than 0.3 eV, still further less than 0.2 eV.
Examples of the anode material include, but are not limited to, Al,
Cu, Au, Ag, Mg, Fe, Co, Ni, Mn, Pd, Pt, ITO, aluminum-doped zinc
oxide (AZO), and the like. Other suitable anode materials are known
and may be easily selected by one of ordinary skilled in the art.
The anode material may be deposited by any suitable technologies,
such as the suitable physical vapor deposition method which
includes radio frequency magnetron sputtering, vacuum thermal
evaporation, electron beam, and the like.
In some embodiments, the anode is patterned and structured.
Patterned ITO conductive substrates are commercially available and
can be used to prepare the device according to the present
disclosure.
Cathode 106 may comprise a conductive metal or metal oxide. The
cathode can easily inject electrons into the EIL or ETL or directly
into the light emitting layer. In an embodiment, the absolute value
of the difference between the work function of the cathode and the
LUMO energy level or the conduction band energy level of the n-type
semiconductor material as the EIL or ETL or HBL is less than 0.5
eV, further less than 0.3 eV, still further less than 0.2 eV. In
principle, all materials that can be used as cathodes for OLED can
be used as cathode materials for the devices of the disclosure.
Examples of the cathode material include: Al, Au, Ag, Ca, Ba, Mg,
LiF/Al, MgAg alloy, BaF2/Al, Cu, Fe, Co, Ni, Mn, Pd, Pt, ITO and
the like. The cathode material may be deposited by any suitable
technologies, such as the suitable physical vapor deposition method
which includes radio frequency magnetron sputtering, vacuum thermal
evaporation, electron beam, and the like.
The light-emitting layer 104 includes at least one light-emitting
functional material, which has a thickness between 2 nm and 200 nm.
In an embodiment, in the light-emitting device according to the
disclosure, the light emitting layer is prepared by printing the
printing ink of the disclosure, wherein the printing ink comprises
at least one light-emitting functional material as described above,
in particular quantum dots or an organic functional material.
In an embodiment, a light emitting device according to the present
disclosure further comprises a hole injection layer (HIL) or hole
transport layer (HTL) 103 comprising an organic HTM or inorganic
p-type material as described above. In a preferred embodiment, the
HIL or HTL may be prepared by printing the printing ink of the
present disclosure, wherein the printing ink contains a functional
material having hole transporting capability, particularly quantum
dots or an organic HTM material.
In another embodiment, a light emitting device according to the
present disclosure further comprises an electron injection layer
(EIL) or electron transport layer (ETL) 105 comprising an organic
ETM or inorganic n-type material as described above. In some
embodiments, the EIL or ETL can be prepared by printing the
printing ink of the present disclosure, wherein the printing ink
contains functional materials having electron transport capability,
particularly quantum dots or organic ETM materials.
The disclosure further relates to the use of a light emitting
device according to the disclosure in various applications,
including, but not limited to, various display devices, backlights,
illumination sources, and the like.
The present disclosure will be described with reference to the
preferred embodiments thereof, but the present disclosure is not
limited to the examples described below. It is to be understood
that the appended claims are intended to cover the scope of the
disclosure. Under the guidance of the inventive concept, those
skilled in the art should be aware that some modifications of the
various embodiments of the disclosure are intended to be covered by
the scope of the appended claims.
EXAMPLES
Example 1: Preparation of Blue Light Quantum Dots (CdZnS/ZnS)
0.0512 g of S and 2.4 mL of octadecene (ODE) were added in a 25 mL
single-necked flask, which was then heated in an oil pan to
80.degree. C. to dissolve S for use, hereafter referred to as
Solution 1; 0.1280 g of S and 5 mL of oleylamine (OA) were added in
a 25 mL single-necked flask, which was then heated in an oil pan to
90.degree. C. to dissolve S for use, hereinafter referred to as
Solution 2; 0.1028 g of CdO, 1.4680 g of zinc acetate and 5.6 mL of
OA were added in a 50 mL three-necked flask. In a 150 mL heating
mantle the three-necked flask was placed with two side necks
plugged with rubber plugs and top neck connected to a condenser
connected to a double tube, and was heated to 150.degree. C.,
evacuated for 40 min, and then filled with nitrogen gas; 12 mL of
ODE were added to the three-necked flask using a syringe, and
three-necked flask was heated to 310.degree. C., once the
temperature was reached, 1.92 mL of Solution 1 was rapidly added
into the three-necked flask using a syringe. after 12 min, with a
syringe 4 mL of Solution 2 was added dropwise to the three-necked
flask with dropping rate of approximately 0.5 mL/min, and the
reaction was performed for 3 h. After the reaction is stopped, the
three-necked flask immediately was put into water to cool down to
150.degree. C.;
An excess of n-hexane was added to the three-necked flask, and then
the liquid in the three-necked flask was transferred to a plurality
of 10 mL centrifuge tubes, centrifuged to remove the lower layer
precipitate, and repeated three times; acetone was added to the
liquid after the post-treatment 1 until precipitation occurred, the
tubes were centrifuged to remove the supernatant and leave a
precipitate; the precipitate was then dissolved with n-hexane,
acetone was added until precipitation occurred, and the tubes were
centrifuged to remove the supernatant and leave a precipitate, this
process was repeated for three times; Finally, the precipitate was
dissolved in toluene, and the result was transferred to a glass
bottle for storage.
Example 2: Preparation of Green Light Quantum Dots
(CdZnSeS/ZnS)
0.0079 g of selenium and 0.1122 g of sulfur and 2 mL of
trioctylphosphine (TOP) were added and stirred in a 25 mL
single-necked flask which was filled with nitrogen gas, hereinafter
referred to as Solution 1; 0.0128 g of CdO and 0.3670 g of zinc
acetate and 2.5 mL of OA were added in a 25 mL three-necked flask.
In a 50 mL heating mantle the three-necked flask was placed with
two side necks plugged with rubber plugs and top neck connected to
a condenser connected to a double tube, and was evacuated, and then
filled with nitrogen gas, heated to 150.degree. C., and evacuated
for 30 min before 7.5 mL of ODE injected thereinto, and
three-necked flask was heated to 300.degree. C., once the
temperature was reached, 1 mL of Solution 1 was rapidly injected.
After 10 min, the reaction is stopped, the three-necked flask
immediately was put into water to cool down.
5 mL of n-hexane was added to the three-necked flask, and the
mixture was added to a plurality of 10 mL centrifuge tubes, acetone
was added until precipitation occurred, and centrifugation was
carried out. The precipitate was taken, the supernatant was
removed, the precipitate was dissolved with n-hexane, acetone was
added until precipitation occurred, and centrifugation was carried
out. This process was repeated for three times. The final
precipitate was dissolved in a small amount of toluene, and the
result transferred to a glass bottle for storage.
Example 3: Preparation of Red Light Quantum Dots (CdSe/CdS/ZnS)
1 mmol of CdO, 4 mmol of OA and 20 ml of ODE were added to a 100 ml
three-necked flask, which was then filled with nitrogen and heated
to 300.degree. C. to formed a Cd(OA).sub.2 precursor. At this
temperature, 0.25 mL of TOP dissolving 0.25 mmol of Se powder was
quickly injected. The reaction solution was reacted at this
temperature for 90 seconds to obtain CdSe cores of about 3.5 nm.
0.75 mmol of octyl mercaptan was added dropwise to the reaction
solution at 300.degree. C., and CdS shells of about 1 nm thick was
grown after 30 minutes of reaction. 4 mmol of Zn(OA).sub.2, and 2
ml of TBP dissolved in 4 mmol of S powder were then added dropwise
to the reaction solution to grow a ZnS shells (about 1 nm). After
the reaction was continued for 10 minutes, it was cooled to room
temperature.
5 mL of n-hexane was added to the three-necked flask, and the
mixture was added to a plurality of 10 mL centrifuge tubes, acetone
was added until precipitation occurred, and centrifugation was
carried out. The precipitate was taken, the supernatant was
removed, the precipitate was dissolved with n-hexane, acetone was
added until precipitation occurred, and centrifugation was carried
out. This process was repeated for three times. The final
precipitate was dissolved in a small amount of toluene, and the
result transferred to a glass bottle for storage.
Example 4: Preparation of ZnO Nanoparticles
1.475 g of zinc acetate was dissolved in 62.5 mL of methanol to
give a Solution 1. 0.74 g of KOH was dissolved in 32.5 mL of
methanol to give a solution 2. Solution 1 was warmed to 60.degree.
C. with stirring vigorously. Solution 2 was added dropwise to
Solution 1 using an injector. After the completion of the dropwise
addition, the mixed solution system was further stirred at
60.degree. C. for 2 hours. The heat source was removed and the
solution system was allowed to stand for 2 hours. The reaction
solution was centrifuged three times or more using a centrifugal
condition of 4500 rpm for 5 minutes. Finally, a white solid was
obtained as ZnO nanoparticles having a diameter of about 3 nm.
Example 5: Preparation of Quantum Dot Printing Ink Containing
Quinoline and 1-Tetralone
Quinoline (5.7 g) and 1-tetralone (3.8 g) solvents were weighed
separately (weight ratio 60:40). A vial in which the stirrer was
placed was cleaned and transferred to the glove box. The quantum
dots were precipitated from the solution with acetone and
centrifuged to obtain a quantum dot solid. In the glove box 0.5 g
of quantum dot solid was weighed, and added to the quinoline
solvent in the vial, and stirred at 60.degree. C. until the quantum
dots were completely dispersed, then 1-tetralone solvent was added
to obtain a mixed solution and stirred until the quantum dots were
completely dispersed, then the solution was cooled to room
temperature. The obtained quantum dot solution was filtered through
a 0.2 m PTFE filter and sealed for storage.
Example 6: Preparation of ZnO Nanoparticle Printing Ink Containing
Acetophenone and 3-Isopropylbiphenyl
Acetophenone (5.7 g) and 3-isopropylbiphenyl (3.8 g) solvents were
weighed (weight ratio 60:40). A vial in which the stirrer was
placed was cleaned and transferred to the glove box. In the glove
box 0.5 g of ZnO nanoparticles solid was weighed, and added to the
acetophenone solvent in the vial, and stirred at 60.degree. C.
until the ZnO nanoparticles are completely dispersed, then
3-isopropylbiphenyl solvent was added to obtain a mixed solution
and stirred until the ZnO nanoparticles were completely dispersed,
then the solution was cooled to room temperature. The obtained
solution of ZnO nanoparticles was filtered through a 0.2 m PTFE
filter and sealed for storage.
The organic functional materials involved in the following examples
are all commercially available, such as Jilin OLED Material Tech
Co., Ltd. (www.jl-oled.com), or synthesized according to methods
reported in the literature.
Example 7: Preparation of Printing Ink of Organic Light-Emitting
Layer Material Containing Chloronaphthalene and
3-Phenoxytoluene
In this example, the organic light-emitting layer functional
material comprises a phosphorescent host material and a
phosphorescent emitter material. The phosphorescent host material
is selected from a carbazole derivative as follows:
##STR00092##
The phosphorescent emitter material is selected from a ruthenium
complex as follows:
##STR00093##
Chloronaphthalene (5.88 g) and 3-phenoxytoluene (3.92 g) solvent
(weight ratio 60:40) were weighed. A vial in which the stirrer was
placed was cleaned and transferred to the glove box. In the glove
box, 0.18 g of the phosphorescent host material and 0.02 g of the
phosphorescent emitter material was weighed, and added to the
chloronaphthalene solvent in the vial, and stirred for mixing. The
mixture was stirred at 60.degree. C. until the organic functional
material was completely dissolved, then 3-phenoxytoluen solvent was
added to obtain a mixed solution and stirred until the organic
functional material was completely dissolved, then the solution was
cooled to room temperature. The obtained solution of organic
functional material was filtered through a 0.2 m PTFE filter and
sealed for storage.
Example 8: Preparation of Printing Ink of Organic Light-Emitting
Layer Material Containing Pentylbenzene and Isononyl
Isononanoate
In this example, the organic light-emitting layer functional
material comprises a fluorescent host material and a fluorescent
emitter material.
The fluorescent host material is selected from a spirofluorene
derivative as follows:
##STR00094##
The fluorescent emitter material is selected from a compound as
follows:
##STR00095##
Pentylbenzene (5.88 g) and isononyl isononanoate (3.92 g) solvent
(weight ratio 60:40) were weighed. A vial in which the stirrer was
placed was cleaned and transferred to the glove box. In the glove
box, 0.19 g of the fluorescent host material and 0.01 g of the
phosphorescent emitter material was weighed, and added to the
pentylbenzene solvent in the vial, and stirred for mixing. The
mixture was stirred at 60.degree. C. until the organic functional
material was completely dissolved, then isononyl isononanoate
solvent was added to obtain a mixed solution and stirred until the
organic functional material was completely dissolved, then the
solution was cooled to room temperature. The obtained solution of
organic functional material was filtered through a 0.2 .mu.m PTFE
filter and sealed for storage.
Example 9: Preparation of Printing Ink of Organic Light-Emitting
Layer Material Containing 3-Phenoxytoluene and Sulfolane
In this example, the organic light-emitting layer functional
material comprises a host material and a TADF material.
The host material is selected from a compound as follows:
##STR00096##
The TADF material is selected from a compound as follows:
##STR00097##
3-phenoxytoluene (5.88 g) and sulfolane (3.92 g) solvent (weight
ratio 60:40) were weighed. A vial in which the stirrer was placed
was cleaned and transferred to the glove box. In the glove box,
0.18 g of the host material and 0.02 g of the TADF material was
weighed, and added to the 3-phenoxytoluene solvent in the vial, and
stirred for mixing. The mixture was stirred at 60.degree. C. until
the organic functional material was completely dissolved, then
sulfolane solvent was added to obtain a mixed solution and stirred
until the organic functional material was completely dissolved,
then the solution was cooled to room temperature. The obtained
solution of organic functional material was filtered through a 0.2
.mu.m PTFE filter and sealed for storage.
Example 10: Preparation of Printing Ink of Hole Transport Material
Containing Tetrahydronaphthalene and Dodecylbenzene
In this example, the printing ink comprises a hole transport layer
material having a hole transporting capability.
The hole transport material is selected from a triarylamine
derivative as follows:
##STR00098##
Tetrahydronaphthalene (5.88 g) and dodecylbenzene (3.92 g) solvent
(weight ratio 60:40) were weighed. A vial in which the stirrer was
placed was cleaned and transferred to the glove box. In the glove
box, 0.2 g of the hole transport material was weighed, and added to
the tetrahydronaphthalene solvent in the vial, and stirred for
mixing. The mixture was stirred at 60.degree. C. until the organic
functional material was completely dissolved, then dodecylbenzene
solvent was added to obtain a mixed solution and stirred until the
organic functional material was completely dissolved, then the
solution was cooled to room temperature. The obtained solution of
organic functional material was filtered through a 0.2 m PTFE
filter and sealed for storage.
Example 11: Viscosity and Surface Tension Test
The viscosity of the functional material ink was tested by a DV-I
Prime Brookfield rheometer; the surface tension of the functional
material ink was tested by a SITA bubble pressure tension
meter.
According to the above test, the functional material ink obtained
in Example 5 had a viscosity of 6.3.+-.0.5 cPs and a surface
tension of 43.2.+-.0.3 dyne/cm.
According to the above test, the functional material ink obtained
in Example 6 had a viscosity of 4.7.+-.0.3 cPs and a surface
tension of 36.2.+-.0.3 dyne/cm.
According to the above test, the functional material ink obtained
in Example 7 had a viscosity of 4.2.+-.0.3 cPs and a surface
tension of 39.6.+-.0.5 dyne/cm.
According to the above test, the functional material ink obtained
in Example 8 had a viscosity of 3.8.+-.0.3 cPs and a surface
tension of 29.1.+-.0.3 dyne/cm.
According to the above test, the functional material ink obtained
in Example 9 had a viscosity of 6.7.+-.0.5 cPs and a surface
tension of 35.9.+-.0.5 dyne/cm.
According to the above test, the functional material ink obtained
in Example 10 had a viscosity of 3.6.+-.0.5 cPs and a surface
tension of 33.1.+-.0.5 dyne/cm.
A functional layer in the light-emitting diode, such as a
light-emitting layer and a charge transport layer, can be prepared
by inkjet printing using the printing ink containing a functional
material based on the two organic solvent systems prepared above,
and the specific steps are as follows.
The ink containing the functional material is loaded into an ink
tank that is assembled to an inkjet printer such as Dimatix
Materials Printer DMP-3000 (Fujifilm). The waveform, pulse time and
voltage of ink jetting are adjusted to optimize ink jetting and to
stabilize the inkjet range. In the preparation of an organic
light-emitting diode/quantum dot light-emitting diode (OLED/QLED)
device in which the functional material film is a light-emitting
layer, the following technical solution is adopted: The substrate
of the OLED/QLED is a 0.7 mm thick glass sputtered with an indium
tin oxide (ITO) electrode pattern. The pixel defining layer is
patterned on the ITO to form an internal hole for depositing the
printing ink. The HIL/HTL material is then inkjet printed into the
hole and the solvent is removed by drying at a high temperature in
a vacuum to obtain a HIL/HTL film. Thereafter, the printing ink
containing the light emitting functional material is ink-jet
printed onto the HIL/HTL film, and the solvent is removed by drying
at a high temperature in a vacuum to obtain a light emitting layer
film. Subsequently, a printing ink containing a functional material
having electron transporting properties is ink-jet printed onto the
light emitting layer film, and the solvent is removed by drying at
a high temperature in a vacuum to form an electron transport layer
(ETL). When using organic electron transport materials, ETL can
also be formed by vacuum thermal evaporation. Then, the Al cathode
is formed by vacuum thermal evaporation, followed by packaging to
complete the preparation of the OLED/QLED device.
The technical features of the above-described embodiments may be
combined arbitrarily. To simplify the description, all the possible
combinations of the technical features in the above embodiments are
not described. However, all of the combinations of these technical
features should be considered as within the scope of the present
disclosure, as long as such combinations do not contradict with
each other.
The above-described embodiments merely represent several
embodiments of the present 5 disclosure, and the description
thereof is more specific and detailed, but it should not be
construed as limiting the scope of the present disclosure. It
should be noted that, for those skilled in the art, several
variations and improvements may be made without departing from the
concept of the present disclosure, and these are all within the
protection scope of the present disclosure.
* * * * *